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2016年11月10日 星期四

N-酒神

The Greeks, who simultaneously declare and conceal the mystery of their view of the world in their gods, established as the double source of their art two deities, Apollo and Dionysos. In the realm of art these names represent stylistic opposites which exist side by side and in almost perpetual conflict with one another, and which only once, at the moment when the Hellenic Will' blossomed, appeared fused together in the work of art that is Attic tragedy. For there are two states in which human beings attain to the feel-ing of delight in existence, namely in dream and in intoxication. Every human being is fully an artist when creating the worlds of dream, and the lovely semblance of dream is the father of all the arts of image-making, including, as we shall see, an important half of poetry. We dream with pleasure as we understand the figure directly; all forms speak to us; nothing is indifferent or unnecessary. Yet even while this dream-reality is most alive, we nevertheless retain a pervasive sense that it is semblance; only when this ceases to be the case do the pathological effects set in whereby dream no longer enlivens and the healing natural energy of its states ceases. Within that boundary, however, it is not just the pleasant and friendly images in us which we seek out with that complete sense of comprehen-sion; things which are grave, sad, gloomy, and dark are contemplated with just as much pleasure, always provided that here too the veil of semblance is in fluttering movement and does not completely cover up the basic forms of the real. Thus, whereas in dream the individual human being plays with the real, the art of the image-maker (in the wider sense) is a playing with dream. As a block of marble the statue is something very real, but the reality of the statue as a dream figure is the living person of the god. As long as the statue hovers as an image of fantasy before the eyes of the artist, he (p20)is still playing with the real; when he translates this image into marble, he is playing with dream.

Now, in what sense could Apollo be made into a god of art? Only inas-much as he is the god of dream-representations. He is the 'luminous one' through and through; at his deepest root he is a god of the sun and light who reveals himself in brilliance. 'Beauty' is his element, eternal youth his companion. But the lovely semblance of the world of dreams is his realm too; the higher truth, the perfection of these dream-states in contrast to the only partially intelligible reality of the daylight world, raise him to the status of a prophetic god, but equally certainly to that of an artistic god. The god of lovely semblance must be the god of true knowledge as well. But the image of Apollo must also include that delicate line which the dream image must not overstep if its effect is not to become pathological, in which case the semblance does not simply deceive but also cheats; it must include that measured limitation, that freedom from wilder impulses, that wise calm of the image-making god. His eye must be 'sun-like' and calm; even when it is angry and shows displeasure, the consecrated aura of lovely semblance surrounds it.

Dionysiac art, by contrast, is based on play with intoxication, with the state of ecstasy. There are two principal forces which bring naive, natural man to the self-oblivion of intense intoxication: the drive of spring and narcotic drink. Their effects are symbolized in the figure of Dionysos. In both states the principium individuationis is disrupted, subjectivity dis-appears entirely before the erupting force of the general element in human life, indeed of the general element in nature. Not only do the festivals of Dionysos forge a bond between human beings, they also reconcile human beings and nature. Freely the earth brings its gifts, the fiercest beasts approach one another in peace; the flower-decked chariot of Dionysos is drawn by panthers and tigers. All the caste-like divisions which necessity and arbitrary power have established between men disappear; the slave is a free-man, the aristocrat and the man of lowly birth unite in the same Bacchic choruses. In ever-swelling bands the gospel of 'universal harmony' rolls on from place to place; as they sing and dance, human beings express their membership of a higher, more ideal community; they have forgotten how to walk and speak. Yet it is more than this: they feel themselves to have been transformed by magic, and they really have become something different. Just as the animals now talk and the earth gives milk and honey, something supernatural now sounds out from within man. He feels him-(21) self to be a god; that which had previously lived only in his imagination he now feels in his own person. What does he now care for images and statues? Man is no longer an artist, he has become a work of art; man him-self now moves with the same ecstasy and sublimity with which, in dream, he once saw the gods walk. The artistic force of nature, not that of an individual artist, reveals itself here; a nobler clay, a more precious marble is kneaded and chiselled here: the human being. This human being whom the artist Dionysos has formed stands in the same relation to nature as a statue does to the Apolline artist.

If intoxication is nature playing with human beings, the Dionysiac artist's creation is a playing with intoxication. If one has not experienced it for oneself this state can only be understood by analogy; it is rather like dreaming and at the same time being aware that the dream is a dream. Thus the attendant of Dionysos must be in a state of intoxication and at the same time he must lie in ambush, observing himself from behind. Dionysiac art manifests itself, not in the alternation of clear-mindedness and intoxi-cation, but in their co-existence.

This co-existence marks the high point of Hellenic culture; originally, only Apollo is a Hellenic god of art, and it was his power which so moder-ated Dionysos when he came storming in from Asia that the most beauti-ful brotherly bond could come about. Nowhere can the incredible idealism of the Hellenic race be grasped more readily than here: a cult of nature which, amongst the peoples of Asia, had meant the crudest unleashing of the lower drives, a panhetaerici animality which sundered all social ties for a certain period of time, was transformed amongst the Hellenes into a festival of universal redemption, a day of transfiguration. All the sublime drives of their character were revealed in this idealization of orgy.

Yet never was the Hellenic world in greater danger than during the stormy approach of the new god. Conversely, the wisdom of the Delphic god never showed itself in a more beautiful light. Reluctantly at first, he laid the finest of webs about his powerful antagonist so that the latter could hardly tell that he was wandering about in semi-captivity. When the Delphic priesthood perceived that the new cult had a profound effect on the processes of social regeneration, and promoted it in line with their political and religious intention; when the Apolline artist, with thoughtful moderation, learned from the revolutionary art of the rites of Bacchus; and, finally, when, in the ordering of the Delphic cult, sovereignty over the year (22)was shared between Apollo and Dionysos, both gods emerged victorious, as it were, from their contest: an act of reconciliation on the battlefield. Anyone who wants to see clearly just how powerfully the Apolline element held down the irrational, supernatural quality of the Dionysiac element, should consider that in the older period of music the genos dithyrambikon was also the hesuchastikon.2 The more vigorously the Apolline spirit of art now flourished, the more freely did his brother-god Dionysos develop; in the same period as the first of them was attaining to the full, one might say immobile, vision of beauty, at the time of Phidias,3 the other was interpreting the mysteries and terrors of the world in tragedy and giving voice in the music of tragedy to the innermost thought of nature: the weaving of the Will' in and above all appearances.

If music, too, is Apolline art, this applies, strictly speaking, only to rhythm, the image-creating energy of which was developed to represent Apolline states; the music of Apollo is architecture in sound, and, what is more, in the merely hinted-at sounds characteristic of the cithara. Cautiously it holds at a distance precisely that element which defines the character of Dionysiac music (and thus of music generally), the power of musical sound to shake us to the core and the quite incomparable world of harmony. The Greeks had the finest feeling for harmony, as their strict characterization of the modes obliges us to conclude, although the need for an elaborated, truly audible harmony was much weaker amongst them than it is in the modern world. In the sequence of harmonies, and even in their abbreviated form, so-called melody, the Will' reveals itself directly, with-out previously having embodied itself in a phenomenon. Every individual can, as it were, serve as a likeness, as an individual instance of a general rule; conversely, however, the Dionysiac artist presents the essence of everything that appears in a way that is immediately intelligible, for he has command over the chaos of the Will before it has assumed individual shape, and from it he can bring a new world into being at each creative moment, but also the old world with which we are already familiar as phenomenon. In this latter sense he is a tragic musician.

 Nature expresses itself with its highest energy in Dionysiac intoxication, in the tumultuous, wild chase across all the scales of the soul under the influence of narcotic stimulants or when the drives of spring are unleashed; it binds individual creatures together again, and it makes them feel that (23)they are one with each other, so that the principium individuationis appears, so to speak, to be a perpetual state of weakness of the Will. The more degenerate the Will is, the more everything fragments into individual elements; the more selfish and arbitrary the development of the individual, the weaker is the organism which it serves. This is why there erupts in those states what one might call a sentimental (sentimentalisch) tendency in the Will, a 'sigh of the creature' for what is lost; out of highest joy there comes a cry of horror, the yearning sounds of lament at some irredeemable loss. Abundant nature celebrates its saturnalian festivals and its rites of death at one and the same time. The affects of its priests are most won-drously mixed, pain awakens delight, rejoicing wrings sounds of agony from the breast. The god ho lysios4 has transformed everything, redeemed and released everything from itself. The singing and the expressive gestures of a mass stimulated in this manner, and in whom nature acquired a voice and movement, was something new and unheard-of in the Homeric-Greek world; it struck the Greeks as something Oriental which they first had to tame with their enormous rhythmic and image-making energy, and which they did indeed tame, just as they tamed the Egyptian temple-style at the same time. It was the Apolline people who laid the chains of beauty on over-mighty instinct, who yoked and harnessed nature's most dangerous elements, her wildest beasts. The idealistic power of the Hellenic character is seen at its most admirable when one compares its spiritualization of the festival of Dionysos with what emerged from the same origin amongst other peoples. Similar festivals are very ancient and their existence is demonstrable everywhere, most notably in Babylon where they are known as the sacaea. Here, during five-day-long festivals, every political and social bond was torn apart; but the centre of the cult lay in the absence of all sexual discipline, in the destruction of all family life by un-restrained hetaerism. The very antithesis of this is to be found in the image of the Greek festivals of Dionysos, as drawn by Euripides in his Bacchae,5 an image which radiates the same loveliness, the same transfiguring musi-cal intoxication as Skopas and Praxiteles6 embodied in their statues. A messenger describes how he had withdrawn with his herds to the very peaks of the mountains during the midday heat; this is the right moment and the right place to see the unseen; Pan is now asleep, the sky is now the unmoving background of a glory, the day now blossoms. On an alpine meadow the messenger notices three choruses of women lying in scattered (24) groups on the ground and in decorous pose; many women stand leaning against pine trees; all slumber. Suddenly the mother of Pentheus breaks out in jubilation, sleep is banished, all leap to their feet, a model of noble comportment; the young girls and the women let their locks fall to their shoulders, the doe-skin is put in order if its ribbons and bows have become loosened during sleep. They gird themselves about with snakes which lick their cheeks confidingly, some women take young wolves and deer in their arms and suckle them. All adorn themselves with garlands of ivy; when the thyrsus is struck against a rock water bubbles forth, and when the earth is struck with a staff a fountain of wine rises up. Sweet honey drops from the twigs, and when someone touches the earth with just the tips of their fingers snow-white milk springs forth. This is an utterly enchanted world, nature celebrates its festival of reconciliation with mankind. The myth recounts that Apollo joined Dionysos together again after he had been dismembered. This is the image of Dionysos created anew by Apollo and saved from his Asiatic dismemberment.

2

The Greek gods, in the perfection with which they already appear in Homer, are certainly not to be understood as having been born of calamity and need; it is certain that such creatures were not conceived by a heart shaken by fear; it was not to turn away from life that a genial fantasy projected their images into the blue. What speaks out of them is a religion of life, not one of duty or asceticism or spirituality. All these figures breathe the triumph of existence, a luxuriant vitality accompanies their cult. They do not make demands; all that exists is deified in them, regardless of whether it is good or evil. Measured against the gravity, the sanctity and severity of other religions, Greek religion is in danger of being under-estimated as a playful fantasy — unless one includes in one's representation of it an often overlooked trait of most profound wisdom, so that the Epicurean life of the gods suddenly appears to be a creation of that incom-parable artist-people, indeed almost as its supreme creation. It is the philosophy of the people which the captive wood-god unveils to mortals: `The best is not to be, the second best to die soon.' It is this same phil-osophy which forms the background of that pantheon. The Greeks knew the terrors and horrors of existence, but they covered them with a veil in order to be able to live: a cross hidden behind roses, to adopt Goethe's (25) symbol. That luminous Olympian company only came to rule so that the sombre sway of moira, which determined Achilles' early death and the horrifying marriage of Oedipus, should be hidden by the radiant figures of Zeus, Apollo, Hermes, etc. If someone had removed the artistic semblance of that middle world, the Greeks would have had to follow the wisdom of the wood-god, the companion of Dionysos. It was out of this necessity that the artistic genius of this people created these gods. For this reason, theodicy was never a Hellenic problem; they took care never to attribute the exis-tence of the world, and hence responsibility for the way it is, to the gods. The gods, too, are subject to ananke;8 this is a confession of the rarest wisdom. To view its own existence in a transfiguring mirror and to protect itself with this mirror against the Medusa — this was the genial strategy adopted by the Hellenic Will' in order to be able to live at all. For how else could that infinitely sensitive people with such brilliant talent for suffering have been able to bear life, if that self-same life had not been revealed to them in their gods, suffused with a higher glory! The same drive which summons art into being in order to perfect existence, to augment it and seduce men into continuing to live, also led to the creation of the Olympian world, a world of beauty, calm and pleasure.

Under the influence of such a religion life is understood in the Homeric world as that which is inherently desirable: life beneath the sunshine of such gods. The pain of Homeric man related to departure from this exist-ence, above all to imminent departure. If a lament is heard at all, it sings again of short-lived Achilles, of the rapid succession of the generations of mankind, of the passing of the heroic age. It is not unworthy of the great-est hero to long to go on living, even as a day-labourer. The Will' never expressed itself more plainly than in the Hellenes, whose very lament is still a song of praise. For this reason modern man feels a longing for that time when he believes he can hear nature and mankind in complete harmony; for this reason the Hellenic is the solution for all those who need to look about them for radiant models for the conscious affirmation of their will; for this reason, finally, the concept of 'Greek cheerfulness' has emerged at the hands of pleasure-seeking writers, so that, with an utter lack of respect, a slovenly life of self-indulgence dares to excuse, indeed honour itself, with the word 'Greek'. In all of these representations, ranging from the noblest to the most (26) 
common and misguided, the Greeks are understood in too crude and simple a manner and, to a certain extent, shaped in accordance with the image of unambiguous and, so to speak, one-sided nations (e.g. the Romans). After all, it ought to be suspected that some need for artistic semblance will be present even in the world view of a people which habit-ually turns everything it touches into gold. And we do indeed find, as we have indicated, an enormous illusion in this world view, the same illusion as nature regularly employs to achieve its goals. The true goal is obscured by a deluding image; we stretch out our hands towards the image, and nature achieves its goal by means of this deception. In the Greeks the Will wished to gaze on a vision of itself transfigured in a work of art; in order that the Will might glorify itself, its creatures too had to feel themselves to be worthy of glorification; they had to recognize a reflection of themselves in a higher sphere, elevated to the ideal, as it were, without feeling that the perfected world of their vision was an imperative or a reproach. This is the sphere of beauty in which they see their mirror images, the Olympians. With this weapon the Hellenic Will' fought against the talent for suffering and for the wisdom of suffering that is the correlative of artistic talent. Out of this struggle, and as a monument to its victory, tragedy was born. The intoxication of suffering and the beautiful dream have different pan-theons. By virtue of the omnipotence of its character, the former penetrates to the innermost thoughts of nature, it recognizes the fearful drive to exist and at the same time the perpetual death of everything that comes into existence; the gods which this intoxication creates are good and evil, they resemble chance, they startle us by the sudden emergence of a plan in their actions, they are pitiless and without delight in beauty. They are related to truth and approximate to concepts; rarely and only with difficulty do they become concentrated in figures. Looking at them turns the viewer to stone; how is one to live with them? Yet it is not intended that one should; that is their lesson.


If this pantheon cannot be concealed completely, like some punishable secret, the human gaze must be distracted from it by placing next to it the radiant, dream-born world of the Olympians; this is why the intensity of their colours, the sensuousness of their figures, grows ever greater, the more powerfully truth or its symbol makes its presence felt. Never was the struggle between truth and beauty greater than when the worship of Dionysos invaded Greece; here nature unveiled itself and spoke of its secret with terrifying clarity, in musical sound, in the face of which seductive

2010年10月11日 星期一

筆記:類神經網路

類神經網路(Artificial Neural Networks, ANNs)或譯為人工神經網路,其主要的基本概念是嘗試著模仿人類的神經系統。其架構源自於現今對人類神經系統的認識,它是由很多非線性的運算單元(即:神經元 neuron)和位於這些運算單元間的眾多連結(links)所組成,而這些運算單元通常是以平行且分散的方式來進行運算,如此就可以同時處理大量的資料應用,如:語音、手寫辨識等。

類神經網路是以電腦的軟硬體來模擬生物神經網路的資訊處理系統,從人類專家解決問題的實際案例中學習,利用非線性函數的轉換,能有效地對大量資料進行分析,且具學習能力,以利各種非結構性決策的制定;此外,類神經網路之應用不需前提假設,只要有充足的歷史資料,即可進行分析,例如有完整之水文資訊(雨量、流量或水位資料)的集水區,或精確且眾多的氣象資料,皆十分適合運用網路模式進行分析、預測的工作。
一般類神經網路為三層結構,包含輸入層、隱藏層及輸出層。其中輸入層用以表現輸入變數,其單元數目依問題的型式而定;隱藏層有可能有數層,用以表現輸入處理單元間之交互影響,其單元數目需以試驗的方式決定其最佳數目;輸出層用以表現輸出變數。神經網路的基本原理為網路中靠相關權重連結各層間之單元,各輸入單元輸入值經由加權累加後到達隱藏層,並透過轉換函數可得一值,同理再傳至輸出層。

網路依其架構與學習方式,可用來解決不同類型的問題,常用的類神經網路有:倒傳遞類神經網路、輻狀機底函數類神經網路、自組特徵映射類神經網路、回饋式類神經網路、反傳遞模糊類神經網路、調適性網路模糊推論系統等。
類神經網路已成為熱門的科技議題與發展迅速的應用技術,今日已廣泛地應用在各個領域,從電機、資訊、機械、化工、土木、水利、環工、海洋等理工相關領域,到醫學、農學等生物相關領域及經濟、管理、財務金融等,都可以看到類神經網路的相關研究。許多科學先趨者試著採用模仿生物神經系統之模型—— 類神經網路,來解決一些過去無法解決的問題,其原因大致分為以下幾點:(1) 聯想速度快,(2) 網路架構容易調整,(3) 解決最佳化、非線性等系統問題,(4) 具平行處理特性,(5) 具容錯特性。目前以類神經網路作為解決方案且有良好效果的問題有:語音辨識、文字辨識、天氣預測、股票指數預測、機器人控制、雷達偵測、影像識別、汽車自動駕駛、醫學檢測、蛋白質3D結構檢測等,這也是類神經網路之所以能在短短數十年間,廣受重視且發展迅速之主因。

人工神經網路是一種應用類似於大腦神經突觸聯接的結構進行信息處理的數學模型。在工程與學術界也常直接簡稱為「神經網路」或類神經網路。神經網路是一種運算模型[1],由大量的節點(或稱「神經元」,或「單元」)和之間相互聯接構成。每個節點代表一種特定的輸出函數,稱為激勵函數(activation function)。每兩個節點間的連接都代表一個對於通過該連接信號的加權值,稱之為權重(weight),這相當於人工神經網路的記憶。網路的輸出則依網路的連接方式,權重值和激勵函數的不同而不同。而網路自身通常都是對自然界某種演算法或者函數的逼近,也可能是對一種邏輯策略的表達。
它的構築理念是受到生物(人或其他動物)神經網路功能的運作啟發而產生的。人工神經網路通常是通過一個基於數學統計學類型的學習方法(Learning Method)得以優化,所以人工神經網路也是數學統計學方法的一種實際應用,通過統計學的標準數學方法我們能夠得到大量的可以用函數來表達的局部結構空間,另一方面在人工智慧學的人工感知領域,我們通過數學統計學的應用可以來做人工感知方面的決定問題(也就是說通過統計學的方法,人工神經網路能夠類似人一樣具有簡單的決定能力和簡單的判斷能力),這種方法比起正式的邏輯學推理演算更具有優勢

人工神經元網路模型

通常來說,一個人工神經元網路是由一個多層神經元結構組成,每一層神經元擁有輸入(它的輸入是前一層神經元的輸出)和輸出,每一層(我們用符號記做)Layer(i)是由Ni(Ni代表在第i層上的N)個網路神經元組成,每個Ni上的網路神經元把對應在Ni-1上的神經元輸出做為它的輸入,我們把神經元和與之對應的神經元之間的連線用生物學的名稱,叫做神經軸突的突觸,在數學模型中每個突觸有一個加權數值,我們稱做權重,那麼要計算第i層上的某個神經元所得到的勢能等於每一個權重乘以第i-1層上對應的神經元的輸出,然後全體求和得到了第i層上的某個神經元所得到的勢能,然後勢能數值通過該神經元上的激勵函數(activation function,常是en:Sigmoid function以控制輸出大小,因為其可微分且連續,方便en:Delta rule處理。)求出該神經元的輸出,注意的是該輸出是一個非線性的數值,也就是說通過激勵函數求的數值根據極限值來判斷是否要激活該神經元,換句話說我們對一個神經元網路的輸出是線性不感興趣。

基本結構

一種常見的多層結構的前饋網路(Multilayer Feedforward Network)由三部分組成,
  • 輸入層(Input layer),眾多神經元(Neuron)接受大量非線形輸入信息。輸入的信息稱為輸入向量。
  • 輸出層(Output layer),信息在神經元鏈接中傳輸、分析、權衡,形成輸出結果。輸出的信息稱為輸出向量。
  • 隱藏層(Hidden layer),簡稱「隱層」,是輸入層和輸出層之間眾多神經元和鏈接組成的各個層面。隱層可以有多層,習慣上會用一層。隱層的節點(神經元)數目不定,但數目越多神經網路的非線性越顯著,從而神經網路的強健性(robustness)(控制系統在一定結構、大小等的參數攝動下,維持某些性能的特性。)更顯著。習慣上會選輸入節點1.2至1.5倍的節點。
神經網路的類型已經演變出很多種,這種分層的結構也並不是對所有的神經網路都適用。

無監督式學習網路(Unsupervised Learning Network)是人工智慧網路的一種演算法(algorithm),其目的是去對原始資料進行分類,以便瞭解資料內部結構。有別於監督式學習網路,無監督式學習網路在學習時並不知道其分類結果是否正確,亦即沒有受到監督式增強(告訴它何種學習是正確的)。其特點是僅對此種網路提供輸入範例,而它會自動從這些範例中找出其潛在類別規則。當學習完畢並經測試後,也可以將之應用到新的案例上。