In fact, out of the immense variety in faces, and in the general form of persons, of gestures, fashions of dress, attitudes in rest and motion, which are indelibly impressed on the memory, every one constructs general types for himself; types which are revealed in the allusions made in our daily conversation to the resemblances which we are continually observing. These remain in the memory, with all the manifold resemblances, as well as the ideal of certain types in which the numerous forms we have seen and compared are formulated. We know that when the memory has been dormant, which is often the case, it may be awakened by the stimulus of association, of analogy, or of will, so as to reproduce the forgotten ideas and sensations which are thus again presented to the consciousness. When, therefore, one or more objects are seen in an uncertain light, so as to present a confused appearance of the human form, its general lineaments are unconsciously made by us to correspond with the human type already existing in the memory, and this type presides in the subsequent composition of the reproducing artist who observes the phantasm. The unconscious mental labour which is accomplished in the reproducing cellules of past impressions and ideas by the instantaneous creation of the type, gathers round this type the form and features corresponding with it, which had its earlier existence in our own experience. The external pose and indefinite modification of the objects appear to correspond with the gradual mnemonic revival of the typal form, and they reciprocally stimulate and react on each other. For while a fold, shadow, or line of the objects seen appear to correspond with some feature of the mnemonic type, on the other hand, a fold, shadow, or outline of the object recalls a feature of the inward phantasm composed by the memory. In this process the mnemonic details which are in accordance with the pre-existing type, and sometimes also in accordance with some remarkable face or person which was the first to present itself to the mind, serve as a model for the accidental form of the external object or objects which correspond to it; this in its turn recalls features which remain in the memory, and in this way the external form of this particular phantasm is gradually chiselled into full relief. The more intently we regard the object which is modified to suit the mental image, the more perfectly they agree together, and the apparition stands out with more vivid distinctness. This will be the experience of every one to whom such a phenomenon appears, and a dispassionate analysis of all the phases of this fact must fully confirm our theory.