Letters of C. G. Jung: Volume I, 1906-1950 (Vol 1)
To Sigmund Freud
Dear Professor Freud, 17 May 1912
As regards the question of incest,
I only venture to throw a bold conjecture into the discussion: the large amount of free-floating anxiety in primitive man, which led to the creation of taboo ceremonies inthe widest sense ( totem, etc.), produced among other things the incest taboo as well ( or rather: the mother and father taboo).
The incest taboo does not correspond with the specific value of incest sensu strictiori any more than the sacredness of the totem corresponds with its biological value.
From this standpoint we must say that incest is forbidden not because it is desired but because the free-floating anxiety regressively reactivates infantile material and turns it into a ceremony of atonement ( as though incest had been, or might have been, desired).
Psychologically, the incest prohibition doesn’t have the significance which one must ascribe to it if one assumes the existence of a particularly strong incest wish.
The aetiological significance of the incest prohibition must be compared directly with the so-called sexual trauma, which usually owes its aetiological role only to regressive reactivation.
The trauma is seemingly important or real, and so is the incest prohibition or incest barrier, which from the psychoanalytical point of view has taken the place of the sexual trauma.
Just as cum grano salis it doesn’t matter whether a sexual trauma really occurred or not, or was a mere fantasy, it is psychologically quite immaterial whether an incest barrier really existed or not, since it is essentially a question of later development whether or not the so-called problem of incest will become of apparent importance.
Another comparison: the occasional cases of real incest are of as little importance for the ethnic incest prohibitions as the occasional outbursts of bestiality among primitives are for the ancient animal cults.
In my opinion the incest barrier can no more be explained by reduction to the possibility of real incest than the animal cult can be explained by reduction to real bestiality.
The animal cult is explained by an infinitely long psychological development which is of paramount importance and not by primitive bestial tendencies-these are nothing but the quarry that provides the material for building a temple.
But the temple and its meaning have nothing whatever to do with the quality of the building stones.
This applies also to the incest taboo, which as a special psychological institution has a much greater-and different-significance than the prevention of incest, even though it may look the same from outside.
(The temple is white, yellow, or red according to the material used.)
Like the stones of a temple, the incest taboo is the symbol or vehicle of a far wider and special meaning which has as little to do with real incest as hysteria with the sexual trauma, the animal cult with the bestial tendency and the temple with the stone ( or better, with the primitive dwelling from whose form it is derived).
I hope I have expressed myself a bit more clearly this time.
With many cordial greetings,
JUNG ~Carl Jung, Letters Vol. I, Pages 25-27