energies, and a control of the imponderables of life--those things without physical weight which yet count more in the end than all the masses with which molecular physics has to deal. THE LIBRARY AND THE BUSINESS MAN[16] The electricians have a word that has always interested me--the word and the thing it signifies. It is “hysteresis,” and it means that quality in a mass of iron that resists magnetization, so that if the magnetizing force is a moving one the magnetism always lags a little behind it. We see this quality in many other places besides magnetic bodies--the almost universal tendency of effects to lag behind their causes. I like to watch it in the popular mind--the failure to “catch on” quickly--the appreciation that comes just a little after the thing to be appreciated. Lag everywhere, in apprehension, in knowledge, in the realization of a situation. Everywhere hysteresis. Of course, sometimes the lag is great and sometimes it is slight. It may be affected by physical distance, as when the European thinks that Indians camp in the suburbs of Pittsburg and that the citizens of Indianapolis hunt the buffalo of an evening; or it may be a function of mental distance, as when the Wall Street financier fondly imagines that this country is still populated chiefly by lambs, as it undoubtedly was fifty years ago. I like to watch it as it affects the idea of the public library as some people hold it. Now of course, without progress, change, motion of some kind, there could be no lag. In a permanent magnet there is no hysteresis. If the Indians and the buffalo were still with us, the European would be thinking the truth. If we had not learned that the gold-brick and the green goods were frauds, we could still be fleeced. And if libraries were still what they were fifty years ago, there would be no lag in the ideas that some people hold about them. Libraries have changed. Some of you know it and some of you do not. Libraries have changed in the kind of printed matter that they collect and preserve; in the kind of people to whom they make their appeal; in the way in which they try to make the former available to the latter. They have utterly changed in their own conception of their status in the community, of what they owe to the community and how they ought to go about it, to pay the debt.