The book open at the feet and facing the viewer has a single inscription on the right hand page: "eritis sicut deus" from Genesis 3.5 when the serpent is enticing Eve to eat of the Tree of Knowledge of Good and Evil in the Garden of Eden against the Lord's command, promising "And ye shall be as God [knowing good and evil]"), however the second half of this quote is missing, ripped from the lower half of the page.

Furthermore, when a human is depicted holding a skull, it is usually a comment on mortality (see memento mori) and the inevitability of death; famously, Hamlet bereaves Yorick in one instance, but is soon repulsed by this macabre souvenir as it brings him face-to-face with all life's grim destiny.

"), either suggests Darwinian understanding may lead to Frankenstinian abuse of life's essence, or a more inclusive innocence that recognises a place for other advanced life‑forms on our intellectual podium, if only we can just accommodate those guests.

[4] The page on which the Book of Genensis quote eritis sicut deus (“You will be like God”) is written is torn with the second part Scientes bonum et malum ("knowing good from evil") lost.

Hugo was sympathetic to Darwinian ideas but familiar with Goethe's Faust, where the same quote appears with a warning on the misuse of man's power of reason, the calipers being symbolic of the scientific method.

Other versions less faithful to the original mutate the chimp's pensive contemplation to head‑scratching bewilderment, or sacrifice metallic lustre by substitution of cheaper materials (e.g., clay), and often undermine the sculpture's poise with careless positioning of a plastic skull.