Whether every animal has a fixed type of nourishment.
Further one asks whether every animal has a fixed type of nourishment.
1. And it seems so. For every animal desires nourishment. Therefore, appetite is fixed for a fixed type of nourishment. Since, then, every animal has a fixed appetite, it also has a fixed type of nourishment.
2. Again, this is apparent by induction [per inductionem]. For the bee enjoys honey, but would not enjoy iron, and the hawk enjoys flesh but would not enjoy wood or stones or things of this sort.
The Philosopher says the opposite. This is apparent in the human, who does not fix any nourishment for himself.
One must say that some animals have a fixed nourishment and some do not. For some, for example the hawk and falcons and others of this sort, are very warm and dry and this is why they are nourished only by things very moist and difficult to digest, like raw meats. And some, like bees, have a delicate and frail complexion, and this is why they are nourished only by sweet things. But the human has not only a natural but also a rational appetite, and this is why he does not have a defined nourishment. Rather, by use of his reason he can convert the unsuitable into something suitable and the suitable into something unsuitable. And in this sense some animals, like the dog, imitate the human owing to the indiscriminate nature of their stomach.
1. On to the arguments. To the first, one must reply that not every animal has a defined appetite, since in the human appetite exists with reason, which has the power to incline to contraries.
2. To the second argument one must say that although some animals desire things defined by a natural instinct, nevertheless nothing prevents those which are prudent or capable of reasoning or obedient to reason from having a nourishment that is not fixed.
Whether an animal is born to seek out nourishment more at night than by day.
Further one asks whether an animal is born to seek out nourishment more at night rather than by day.
1. It seems not. Because nothing is seen without light. Therefore one can discover nourishment better during the day than at night.
2. Again, night is better suited for rest than is the day. Therefore each animal has to seek nourishment in the day rather than at night.
The Philosopher says the opposite.
One must say that, for many reasons, some animals seek nourishment more at night than during the day. One can be that a given animal does not tolerate the light of day, like the bat and the owl, but at night its sight is strengthened, etc. Another reason is that they can apprehend their nourishment more stealthily, just as a sheep cannot see a wolf as well at night as it does during the day. Thus, the lion can more quickly catch the stag, and the wolf the sheep, at night rather than during the day. And another cause for this is that the food source of some animals is better revealed at night than during the day, for example mice, which are the cat's food source. And another cause can be that many animals fear humans, who guard the animals' food source. This is why some, like mice, wolves, cats, and ferrets, hunt more at night than during the day, since humans do not guard them at night.
Nevertheless, one must attend to the fact that some animals seek out a food source only during one time of the year, and during the other part of the year they rest and keep themselves in caves, as serpents and lizards do, because they do not tolerate the cold of winter owing to the fragility of their body and the weakness of their heat. Neither does the sparrow or the cuckoo, but rather in winter, asleep and almost dead, they lie concealed. But then their nature returns to the muscles and is fostered in the muscles. This is just as is said of the bear, that for forty days it does not leave its bed nor eat nor drink, but only licks its paws, and it is nourished on that which it sucks up from the paws. Likewise, around the time of the winter solstice bees also lick their feet for forty days and are nourished from that, as is said.
1. On to the arguments. To the first, one must reply that light for some animals is more harmful than helpful, as is the case for the bat owing to the weakness of its vision, which daylight disperses and nighttime unifies, and for this reason etc. And, similarly, some animals see without external light, like the cat, the dog, and others, like the horse.
2. To the second, one must say that night is more a time of rest for gentle animals, but night is more appropriate for animals that lie in wait, because light is hateful to those doing bad things, as is clear in the wolf's case.
-  The Latin here allows both a sense of "apprehend" in the sense of "see" and, more literally, "capture."
-  The received Latin does not make sense ( sed tunc natura eorum recurrit ad musculos et de posito tunc in musculis natura fovetur). If one changes de posito to deposita then the phrase reads, "nature having been deposited then in the muscles," and what we have is a likely doubling of the first phrase ("nature returns to the muscles"). What is most likely is that deposita became corrupted, and another, later hand added natura eorum recurrit ad musculos as an explanation. In any case, the sense is clear enough.