We therefore must not recoil with childish aversion from the examination of the humbler animals. Every realm of nature is marvelous: and as Heraclitus, when the strangers who came to visit him found him warming himself at the furnace in the kitchen and hesitated to go in, reported to have bidden them not to be afraid to enter, as even in that kitchen divinities were present, so we should venture on the study of every kind of animal without distaste; for each and all will reveal to us something natural and something beautiful.

Aristotle (384-322 BC) Greek philosopher
Parts of Animals [De Partibus Animalium], Book 1, part 5 (645a.15) (c. 350 BC) [tr. Ogle (1912)]
    (Source)

Alt. trans.: "For this reason we should not be childishly disgusted at the examination of the less valuable animals. For in all natural things there is something marvelous. Even as Heraclitus is said to have spoken to those strangers who wished to meet him but stopped as they were approaching when they saw him warming himself by the oven -- he bade them enter without fear, "for there are gods here too" -- so too one should approach research about each of the animals without disgust, since in every one there is something natural and good." [tr. Lennox (2001)]