The way to develop this phase of memory is akin to that urged in the development of other phases--the cultivation of interest, and the bestowal of attention. Faces as a whole are not apt to prove interesting. It is only by analyzing and classifying them that the study begins to grow of interest to us. The study of a good elementary work on physiognomy is recommended to those wishing to develop the faculty of remembering faces, for in such a work the student is led to notice the different kinds of noses, ears, eyes, chins, foreheads, etc., such notice and recognition tending to induce an interest in the subject of features. A rudimentary course of study in drawing faces, particularly in profile, will also tend to make one "take notice" and will awaken interest. If you are required to draw a nose, particularly from memory, you will be apt to give to it your interested attention. The matter of interest is vital. If you were shown a man and told that the next time you met and recognized him he would hand you over $500, you would be very apt to study his face carefully, and to recognize him later on; whereas the same man if introduced casually as a "Mr. Jones," would arouse no interest and the chances of recognition would be slim. Halleck says: "Every time we enter a street car we see different types of people, and there is a great deal to be noticed about each type. Every human countenance shows its past history to one who knows how to look.... Successful gamblers often become so expert in noticing the slightest change of an opponent's facial expression that they will estimate the strength of his hand by the involuntary signs which appear in the face and which are frequently checked the instant they appear."