Thus considered, reading is a branch of learning that has no prescribed limits.

It is our duty to learn to read the truth, in the book of nature; I. by collecting separate facts, according to the objective method; II. by proceeding methodically from analysis to synthesis. The subject of our research is the individual human being.

1. The Objective Collecting of Single Facts.—In the gathering of data, our science makes use of two means of investigation, as we have already seen: observation or anthroposcopy; and measurement or anthropometry. In order to take measurements, we must know the special anthropometric instruments and how to use them; and in making observations, we must treat ourselves as instruments, that is, we must divest ourselves of our own personality, of every preconception, in order to become capable of recording the real facts objectively. For since our purpose is to gather our facts from nature and await her revelations, if we allowed ourselves to have scientific preconceptions, we might distort the truth. Here is the point which distinguishes experimental science from a speculative science; in the former, we must banish thought, in the latter we must build by means of thought. Accordingly at the moment when we are collecting our data, we must possess no other capacity than that of knowing how to collect them with extreme exactness and objectivity.

Accordingly we need a method and a mental preparation, that is, a training which will accustom us to divest ourselves of our own personalities, in order to become simple instruments of investigation. For instance, if it were a question of measuring the heads of illiterate children and of other children of the same age, who are attending school, in order to learn whether the heads of educated children show greater development, we need not only to know how to use the millimetric scale and the cranial calipers which are the instruments adapted to this purpose; we need not only to know the anatomical points at which the instruments must be applied in the manner established by the accepted method; but we need in addition to be unaware, while taking the measurements, whether the child before us at a given moment is educated or illiterate because the preconception might work upon us by suggestion and thus alter the result. Or again, to take what in a certain sense is an opposite case, and nevertheless analogous, we may undertake a research into some absolutely unknown question, as for instance, what are the psychic characteristics of children whose development has kept fairly close to the normal average, and of those whose anthropological measurements diverge notably from the average: in such a case we ought to measure all the children, make the required psychological tests separately, and then compare the results of the two investigations.

A woman student in my course, last year, undertook precisely this sort of investigation, namely, to find out what was the standing in school of children who represent the normal average anthropological type, that is to say, those whose physical development had been all that was to be desired: and she found that normal children are vivacious (happy), very intelligent, but negligent; and consequently their number never includes the heads of the classes, the winners of prizes.

In addition to gathering anthropological data, which requires a special technique of research, we need to know how to proceed to interpret them.

We are no longer at the outset of our observations. No sooner was the method established, than there were a multitude of students in all parts of the world capable of objective research, that is to say, of anthropological investigations. The sum total of all these researches forms a scientific patrimony, which needs to be known to us, in order that our own conclusions may serve to complete those of other investigators, who have preceded us, and thus form a contribution to science.

In other words, there have already been certain principles established and certain laws discovered, on an experimental basis; and all this forms a true and fitting content of our science. It will serve to guide us in our researches, and to furnish us with a standard of comparison for our own conclusions. Thus, for example, when we have measured the stature of a boy of ten, we have undoubtedly gathered an individual anthropological fact; but in order to interpret it, we must know what is the average stature of boys of ten; and the average will be found established by previous investigators, who have obtained it from actuality, by applying the well-known method of measuring the stature, to a great number of individuals of a specified race, sex, and age, and by obtaining an average on the basis of such research.

Accordingly, we ought to profit from the researches of others, whenever they have been received, as noteworthy, into the literature of science. Nevertheless, the patrimony which science places at our disposition must never be considered as anything more than a guide, an expression of universal collaboration, in accordance with a uniform method. We must never jurare in verba magistri, never accept any master as infallible: we are always at liberty to repeat any research already made, in order to verify it; and this form of investigation is part of the established method of experimental science. One fundamental principle must be clearly understood; that we can never become anthropologists merely by reading all the existing literature of anthropology, including the voluminous works on kindred studies and the innumerable periodicals; we shall become anthropologists only at the moment when, having mastered the method, we become investigators of living human individuals.

We must, in short, be producers, or nothing at all; assimilation is useless. For example, let us suppose that a certain teacher has studied anthropology in books: if, after that, he is incapable of making practical observations upon his own pupils, to what end does his theoretical knowledge serve him? It is evident that theoretic study can have no other purpose than to guide us in the interpretation of data gathered directly from nature.