There are people who look out and people who look in, and of course there are all sorts of degrees between the two extremes. Some people are wholly preoccupied with their own inner life, their thoughts, their emotions, their experiences. It is only by the pressure of necessity that they force themselves into connection with the world about them, and then it is under protest, and their thoughts leap back, as by a spring, to internal matters, as soon as the pressure is removed. Others live in the swift, diverting movement of the external world and lose their own destiny and almost their identity in the play of it. ‘Let me alone to observe till I turn myself into nothing but observation,’ says the old poet.[2] The observation may be for a serious scientific purpose. It may be for endless entertainment and pure, inexhaustible delight. As Sterne has it: ‘What a large volume of adventures may be grasped within this little span of life by him who interests his heart in everything and who, having eyes to see what time and chance are perpetually holding out to him as he journeyeth on his way, misses nothing he can _fairly_ lay his hands on.’[3] As there are some persons who naturally observe, so there are some who observe certain things, and not others. Women are apt to be more acute observers than men: their senses are more keen and their minds less preoccupied. But their vision is usually limited to the things that interest them. A woman will go into a friend’s house and tell you every detail of furnishing, will describe the friend’s dress with finished minuteness. But she may take a walk through the fields and not be able to remember a single flower or insect. On the other hand, very great scientists will not miss a spider in the grass, but the color of a ribbon may escape them. From another point of view observation may be deliberately exclusive. A trained observer may find that general vision distracts him, and that to follow up his special object it is necessary to put all other sights and sounds out of consideration entirely. Bradford Torrey used to say, and no doubt it is the experience of all naturalists, that if he went to look for a special flower, he saw flowers only, and was quite oblivious to birds, while on bird days a rare blossom might be passed unnoticed.