The Da Vinci Notebooks at sacred-texts.com
Advantages in the structure of the eye in certain animals (828-831).Every object we see will appear larger at midnight than at midday, and larger in the morning than at midday.
This happens because the pupil of the eye is much smaller at midday than at any other time.
In proportion as the eye or the pupil of the owl is larger in proportion to the animal than that of man, so much the more light can it see at night than man can; hence at midday it can see nothing if its pupil does not diminish; and, in the same way, at night things look larger to it than by day.