INDEX 403 HUMAN INTERCOURSE. HUMAN INTERCOURSE. ESSAY I. ON THE DIFFICULTY OF DISCOVERING FIXED LAWS. A book on Human Intercourse might be written in a variety of ways, and amongst them might be an attempt to treat the subject in a scientific manner so as to elucidate those natural laws by which intercourse between human beings must be regulated. If we knew quite perfectly what those laws are we should enjoy the great convenience of being able to predict with certainty which men and women would be able to associate with pleasure, and which would be constrained or repressed in each other's society. Human intercourse would then be as much a positive science as chemistry, in which the effects of bringing substances together can be foretold with the utmost accuracy. Some very distant approach to this scientific state may in certain instances actually be made. When we know the characters of two people with a certain degree of precision we may sometimes predict that they are sure to quarrel, and have the satisfaction of witnessing the explosion that our own acumen has foretold. To detect in people we know those incompatibilities that are the fatal seeds of future dissension is one of our malicious pleasures. An acute observer really has considerable powers of prediction and calculation with reference to individual human beings, but there his wisdom ends. He cannot deduce from these separate cases any general rules or laws that can be firmly relied upon as every real law of nature can be relied upon, and therefore it may be concluded that such rules are not laws of nature at all, but only poor and untrustworthy substitutes for them. The reason for this difficulty I take to be the extreme complexity of human nature and its boundless variety, which make it always probable that in every mind which we have not long and closely studied there will be elements wholly unknown to us. How often, with regard to some public man, who is known to us only in part through his acts or his writings, are we surprised by the sudden revelation of characteristics that we never imagined for him and that seem almost incompatible with the better known side of his nature! How much the more, then, are we likely to go wrong in our estimates of people we know nothing about, and how impossible it must be for us to determine how they are likely to select their friends and companions!