From the 'Poetics,' Chapter 9
But it is evident from what has been said that it is not the province of a poet to relate things which have happened, but such as might have happened, and such things as are possible according to probability, or which would necessarily have happened. For a historian and a poet do not differ from each other because the one writes in verse and the other in prose; for the history of Herodotus might be written in verse, and yet it would be no less a history with metre than without metre. But they differ in this, that the one speaks of things which have happened, and the other of such as might have happened. Hence, poetry is more philosophic, and more deserving of attention, than history. For poetry speaks more of universals, but history of particulars. But universal consists, indeed, in relating or performing certain things which happen to a man of a certain description, either probably or necessarily [to which the aim of poetry is directed in giving names]; but particular consists in narrating what [for example] Alcibiades did, or what he suffered. In comedy, therefore, this is now become evident. For comic poets having composed a fable through things of a probable nature, they thus give whatever names they please to their characters, and do not, like iambic poets, write poems about particular persons. But in tragedy they cling to real names. The cause, however, of this is, that the possible is credible. Things therefore which have not yet been done, we do not yet believe to be possible: but it is evident that things which have been done are possible, for they would not have been done if they were impossible.
Not indeed but that in some tragedies there are one or two known names, and the rest are feigned; but in others there is no known name, as for instance in 'The Flower of Agatho.' For in this tragedy the things and the names are alike feigned, and yet it delights no less. Hence, one must not seek to adhere entirely to traditional fables, which are the subjects of tragedy. For it is ridiculous to make this the object of search, because even known subjects are known but to a few, though at the same time they delight all men. From these things, therefore, it is evident that a poet ought rather to be the author of fables than of metres, inasmuch as he is a poet from imitation, and he imitates actions. Hence, though it should happen that he relates things which have happened, he is no less a poet. For nothing hinders but that some actions which have happened are such as might both probably and possibly have happened, and by [the narration of] such he is a poet.
But of simple plots and actions, the episodic are the worst. But I call the plot episodic, in which it is neither probable nor necessary that the episodes follow each other. Such plots, however, are composed by bad poets, indeed, through their own want of ability; but by good poets, on account of the players. For, introducing [dramatic] contests, and extending the plot beyond its capabilities, they are frequently compelled to distort the connection of the parts. But tragedy is not only an imitation of a perfect action, but also of actions which are terrible and piteous, and actions principally become such (and in a greater degree when they happen contrary to opinion) on account of each other. For thus they will possess more of the marvelous than if they happened from chance and fortune; since also of things which are from fortune, those appear to be most admirable which seem to happen as it were by design. Thus the statue of Mityus at Argos killed him who was the cause of the death of Mityus by falling as he was surveying it. For such events as these seem not to take place casually. Hence it is necessary that fables of this kind should be more beautiful.
ON PHILOSOPHY
Quoted in Cicero's 'Nature of the Gods'
If there were men whose habitations had been always under ground, in great and commodious houses, adorned with statues and pictures, furnished with everything which they who are reputed happy abound with: and if, without stirring from thence, they should be informed of a certain divine power and majesty, and after some time the earth should open and they should quit their dark abode to come to us, where they should immediately behold the earth, the seas, the heavens; should consider the vast extent of the clouds and force of the winds; should see the sun and observe his grandeur and beauty, and perceive that day is occasioned by the diffusion of his light through the sky; and when night has obscured the earth they should contemplate the heavens, bespangled and adorned with stars, the surprising variety of the moon in her increase and wane, the rising and setting of all the stars and the inviolable regularity of their courses,--when, says he, "they should see these things, they would undoubtedly conclude that there are gods, and that these are their mighty works."
ON ESSENCES
From 'The Metaphysics,' Book xi., Chapter I
The subject of theory (or speculative science) is essence. In it are investigated the principles and causes of essences. The truth is, if the All be regarded as a whole, essence is its first (or highest) part. Also, if we consider the natural order of the categories, essence stands at the head of the list; then comes quality; then quantity. It is true that the other categories, such as qualities and movements, are not in any absolute sense at all, and the same is true of [negatives, such as] not-white or not-straight. Nevertheless, we use such expressions as "Not-white is."