ABSTRACT
“COLOUR Vision,” by Dr. Parsons, is so good in itself and so well adapted to bringing to the fore the crucial difficulties of the Helmholtz and of the Hering colour hypotheses that it invites extended discussion. It is not to the physicist and to the follower of Helmholtz that the book is especially calculated to be beneficial; they—alas!—will be too apt to be confirmed in the present error of their ways, for the psychological point of view, which demands explanation of the yellowness of yellow and of the whiteness of white, is a point of view which Dr. Parsons attains to only fleetingly and superficially. Nevertheless, the space which is given to the work of Hering, and the recognition of the widespread acceptance accorded to his views, will perhaps have a subconscious effect in laboratories where his name and his splendid fight for the psychology of colour are practically unknown. It is to the adherents of the other school—the followers of Hering—that the book is destined to be invaluable. It is an attractive piece of book-making—a fact of no little importance; it is freely provided with diagrams—which act as aide-mémoires far better than columns of figures, and which are not, in this instance, like the diagrams of Hering, free-hand drawings based purely upon the imagination; and it offers a thoroughly well-informed and acutely criticized summing-up of the facts regarding colour-sensation, especially those facts which have their origin in the laboratories where Helmholtz is still followed, and which are therefore res non gratœ to too many of the psychologists. Hereafter (on account especially of the evident effort at fairness of this book) it will not be possible for the facts which plainly contradict it to be utterly ignored in the schools where the Hering theory is made a matter of religious faith. (I am personally particularly glad to welcome so strong a defender of some of the doctrines which I have long been preaching.)
