To J. C. Vernon
Dear Sir, 18 June 1957
Since the archetypes are the instinctual forms of mental behaviour it is quite certain that, inasmuch as animals possess a "mind," their mind also follows archetypal patterns, and presumably the same that are operative in the human mind.
As we do not know the actual status of an archetype in the unconscious and only know it in that form in which it becomes conscious, it is impossible to describe the human archetype and to compare it to an animal archetype.
But the hypothesis is that they are the same.
This simply because there is no reason, or at least we don't see one, why it should be otherwise.
If I say that we do not know "the ultimate derivation of the archetype," I mean that we are unable to observe and describe the archetype in its unconscious condition.
When I say that archetypes evolve from instincts, I describe no facts.
It is a mere hypothesis-albeit a likely one.
But actually the facts of this origin are unknown in detail, although we may trace some lines leading into our animal ancestry.
Thus f.i. the religious factor you mention.
It is of course, as you say, an absurdity to isolate the human mind from nature in general.
There is no difference in principle between the animal and the human psyche.
The kinship of the two is too obvious.
C.G. Jung ~Carl Jung, Letters Vol. II, Pages 372-373