There are, of course, many cases in which the conscious acquisition of information is a necessary stage in the acquisition of knowledge. But in all such cases, if the information acquired is to have any educative value, it must be allowed to sink down into the subconscious strata, whence, after having been absorbed and assimilated and so converted into knowledge, it will perhaps reascend towards the surface of the mind, just as the leaves which fall in autumn are dragged down into the soil below, converted into fertile mould, and then gradually lifted towards the surface; or as the fresh water that the rivers pour into the sea has to be slowly absorbed into the whole mass of salt water before it (or its equivalent) can return to the land as rain. When information which has been received and assimilated rises to the surface of the mind, it will be ready, when required to do so, to reappear as information, and perhaps to return in that form to the source from which it came. But the information which is given off will differ profoundly from that which has been received, for between the two will have intervened many stages of silent absorption and silent growth. It may be necessary, then, in the course of education, both to supply and to demand information. But the information which is supplied must be regarded as the raw material of knowledge, into which it is to be converted by a subtle and secret process. And the information which is demanded must be regarded as an exhalation (so to speak) from the surface of a mind which has been saturated with study and experience, and therefore as a proof of the possession of knowledge. To assume that knowledge and information are interchangeable terms, that to impart information is therefore to generate knowledge, that to give back information is therefore to give proof of the possession of knowledge,--is one of the greatest mistakes that a teacher can make.