There is perhaps nothing extraordinary in the fact that man is wise and just, takes great care to provide for his own children, shows due consideration for his parents, seeks sustenance for himself, protects himself against plots, and possesses all the other gifts of nature which are his. For man has been endowed with speech, of all things the most precious, and has been granted reason, which is of the greatest help and use. Moreover, he knows how to reverence and worship the gods. But that dumb animals should by nature possess some good quality and should have many of man's amazing excellences assigned to them along with man, is indeed a remarkable fact. And to know accurately the special characteristics of each, and how living creatures also have been a source of interest no less than man, demands a trained intelligence and much learning. Now I am well aware of the labor that others have expended on this subject, yet I have collected all the materials that I could; I have clothed them in untechnical language, and am persuaded that my achievement is a treasure far from negligible. So if anyone considers them profitable, let him make use of them; anyone who does not consider them so may give them to his father to keep and attend to. For not all things give pleasure to all men, nor do all men consider all subjects worthy of study. Although I was born later than many accomplished writers of an earlier day, the accident of date ought not to deprive me of praise, if I too produce a learned work whose ampler research and whose choice of language make it deserving of serious attention. - [On the Nature of Animals, Book1, Prologue, Scholfield translation]

An example of the chaotic nature of Aelian's book is this excerpt from Book 2, Chapters 33-38. [Scholfield translation]

[33] Many writers tell us about the size of the crocodile both when fully grown and when first hatched, and further, about its tongue, and whether it moves its jaw and which jaw it closes upon the other. There are those too who have observed that this animal lays as many eggs as the days during which it sits upon them before hatching out its young. And I have myself heard that when a crocodile dies a scorpion is born from it; and they do say that it has a sting in its tail which is full of poison.

[34] If these facts are certain and beyond dispute, then let this story from India carry conviction. What I propose to tell has been brought from thence by report and is as follows. I have learnt from the son of Nicomachus that there is a bird named Cinnamon like the plant, and that the bird brings this plant, which is named after it, to the Indians, but that these people have no knowledge where and how the plant grows.

[35] The Egyptians assert that a knowledge of enemas and intestinal purges is derived from no discovery of man's, but they commonly affirm that it was the Ibis that taught them this remedy. And how it instructed those who were the first to see it, some other shall tell. And I have also heard that it knows when the moon is waxing and when waning; and I cannot deny that I have learnt from some source that it diminishes or increases its food according as the goddess herself diminishes or increases.

[36] The Sting-ray in the sea has a far fiercer and more dangerous sting than all other creatures. The proof is that if you fix it in a flourishing tree that has grown to a great height, then without any delay, before any time has elapsed, the tree immediately withers. And if you allow the sting to scratch any living creature, you kill it at once.

[37] So long as the shrew-mouse proceeds as chance directs, it can live, and Nature is on friendly terms with it, unless it is overtaken by misfortune from some other quarter and is killed. When however it falls into a rut, it is caught, so to say, in quite invisible fetters and dies. The remedy for a man who has been bitten by a shrew-mouse is as follows. Take some sand from the wheel-track, sprinkle it on the bite, and it cures him immediately.

[38] Here is another story relating to the Egyptian Ibis which I have heard. The bird is sacred to the moon. At any rate it hatches its eggs in the same number of days that the goddess takes to wax and to wane, and never leaves Egypt. ...