Halleck gives the following excellent advice on this subject: "To look at a thing intelligently is the most difficult of all arts. The first rule for the cultivation of accurate perception is: Do not try to perceive the whole of a complex object at once. Take the human face as an example. A man, holding an important position to which he had been elected, offended many people because he could not remember faces, and hence failed to recognize individuals the second time he met them. His trouble was in looking at the countenance as a whole. When he changed his method of observation, and noticed carefully the nose, mouth, eyes, chin, and color of hair, he at once began to find recognition easier. He was no longer in difficulty of mistaking A for B, since he remembered that the shape of B's nose was different, or the color of his hair at least three shades lighter. This example shows that another rule can be formulated: Pay careful attention to details. We are perhaps asked to give a minute description of the exterior of a somewhat noted suburban house that we have lately seen. We reply in general terms, giving the size and color of the house. Perhaps we also have an idea of part of the material used in the exterior construction. We are asked to be exact about the shape of the door, porch, roof, chimneys and windows; whether the windows are plain or circular, whether they have cornices, or whether the trimmings around them are of the same material as the rest of the house. A friend, who will be unable to see the house, wishes to know definitely about the angles of the roof, and the way the windows are arranged with reference to them. Unless we can answer these questions exactly, we merely tantalize our friends by telling them we have seen the house. To see an object merely as an undiscriminated mass of something in a certain place, is to do no more than a donkey accomplishes as he trots along." There are three general rules that may be given in this matter of bestowing the voluntary attention in the direction of actually _seeing_ things, instead of merely looking at them. The first is: Make yourself take an interest in the thing. The second: See it as if you were taking note of it in order to repeat its details to a friend--this will force you to "take notice." The third: Give to your subconsciousness a mental command to take note of what you are looking at--say to it; "Here, you take note of this and remember it for me!" This last consists of a peculiar "knack" that can be attained by a little practice--it will "come to you" suddenly after a few trials.