Edmond Roudnitska prepared the following papers for presentation at the 9th International Congress of Essential Oils in Singapore. Only the first “Conversation” with André Holley was presented in Singapore because of time constraints. It was read by Stanley E. Allured, Publisher, since Mr. Roudnitska was not able to attend in person. The conversation with André Holley was translated by Paul Johnson, Robertet, in Grasse. The conversation with Maurice Chastrette was translated in the U.S.A. and edited by Mr. Johnson and Mrs. Roudnitska.
A.H.: In your article entitled The student perfumer and his palette (Dragoco Report 1/82), you wrote about the exercise in composition you used to give your students: “exercise no. 1 consists in a very simple mixture of 6 products, all of them constituents of the essence of Neroli, but intermingled in such a way as not to make it too easy. The student will then be asked to reconstruct the composition, i.e., to identify—by smell alone—the constituents and their proportions.”
When one thinks of the skill required to properly prepare this mixture exercise, one is bound to conclude that if a certain number of precautions are not taken while blending the mixture, the student will—with a little care and attention—perceive not a synthesis but distinct elementary olfactory elements. Now, as far as olfactory mechanisms go, this is by no means obvious. For what we know of the way in which receivers work could just as well fit in with the perception of a totally (or almost totally) new form, no special precautions being needed to bring about such a confusion. If an art of the mixture is required in order to achieve a form which does not reveal its constituents, it is because our nervous system spontaneously applies to each peripheral form a treatment aiming at preserving its individuality and allowing it to be recognized even when part of a mixture. Biologically speaking, an analytical perception of the elements of a mixture is of more benefit to the survival of animals than a synthetic one which would erase all peculiarities and prevent the presence of individual constituents from being spotted, thus preventing the perception of olfactory messages pertaining to food, sex, danger. Hence the idea that evolution encouraged the development of nervous mechanisms which only allowed limited possibilities of analysis.