But, in man, almost every thing is accomplished by intelligence; and intelligence supplements instinct.

The opposite is true of animals: their instinct is given them as a supplement to their intelligence.'"-- Flourens: Analytical Summary of the Observations of F.
Cuvier.
"We can form a clear idea of instinct only by admitting that animals have in their _sensorium_, images or innate and constant sensations, which influence their actions in the same manner that ordinary and accidental sensations commonly do.

It is a sort of dream, or vision, which always follows them and in all which relates to instinct they may be regarded as somnambulists."-- F.

Cuvier: Introduction to the Animal Kingdom.
Intelligence and instinct being common, then, though in different degrees, to animals and man, what is the distinguishing characteristic of the latter?
According to F.Cuvier, it is REFLECTION OR THE POWER OF INTELLECTUALLY CONSIDERING OUR OWN MODIFICATIONS BY A SURVEY OF OURSELVES.

This lacks clearness, and requires an explanation.
If we grant intelligence to animals, we must also grant them, in some degree, reflection; for, the first cannot exist without the second, as F.Cuvier himself has proved by numerous examples.