Furthermore, not only is specialization forced upon us by the nature of knowledge, but without it our own powers cannot receive appropriate discipline. It is difficult business to fashion a sound observer. Each province of science has its special modes of observation, its own modes of reasoning even. So long as we are unfamiliar with these and obliged to hold ourselves to them through conscious control, our work is poor. It is slow, inaccurate, and exhausting. Only when we have trained ourselves to such aptitudes that within a certain field our observations and reasonings are instinctive do we become swift, sure, and unfatigued in research. To train our powers then we must begin to specialize early and hold ourselves steadily within bounds. As one looks over the names of those who have accomplished much, one is surprised at the number who were early specialists. Take my own department: Berkeley writes his great work when he is twenty-five; Hume publishes his masterpiece at twenty-seven. Or again, Keats had brought his wonderful results to accomplishment and died at twenty-five; Shelley at thirty; Marlowe, the greatest loss English letters ever met, at twenty-seven. It is just the same in other fields: Alexander dies at thirty-six, Jesus at thirty-three. Yes, let us look nearer home: the most forcible leader American education has ever had became president of Harvard University at thirty-five; President Hyde of Bowdoin took his position at twenty-seven; my own wife, Alice Freeman, was president of Wellesley at twenty-six. These are early specialists; and because they specialized early they acquired an aptitude, a smoothness of work, a precision of insight, and width of power which could not have been theirs had they begun later. I would not deny that there have been geniuses who seemed to begin late: Kant was such; Locke was such. You will recall many within your own fields. But I think when you search the career of those who come to power in comparatively late years, you will find that there has usually been a train of covert specialization running through their lives. They may not have definitely named their field to themselves, or produced work within that field in early years, but everything had been converging toward that issue. I believe, therefore, you ought to respect your specialty, because only through it can your powers be brought to their highest accuracy and service.