This knowledge, belonging not to the organs of sense, but to the mind, constitutes the Sensual plane, g, of the Natural or External Mind. The first few years of the infant's life is largely devoted to the development of this plane. We have observed that a new-born child has no accurate use of its senses. By experience the senses are developed and trained.
The knowledge that must be gathered before the senses become trained and accurate servants of the mind, together with all merely sensual experiences, constitute the Sensual plane of the mind, g, which is the basis of subsequent and higher mental attainments. It is distinctly higher than any plane below it in the diagram, being as much superior as knowledge is to an organ through which it is obtained.
When sensual knowledge is acquired, and thereby a correct use of the senses, a higher order of knowledge can be obtained. Through the use of the senses it is learned that certain seasons follow in succession, that light and heat are essential to life; in short the facts of geography, geology, zoölogy, chemistry, and of all the sciences. This knowledge of facts is proper to the Scientific plane, represented by f, which it fills and forms. The distinction between the Scientific and the Sensual plane is that which exists between the
