=Heredity and environment.=--Let us consider the question in general terms. The characters of any living thing are determined by two factors--heredity and environment. The old phrases were character and circumstances, but they were less than useful, since character is modified by circumstances. Now one of the most important questions in the world, and not least for the eugenist, is as to the relative importance of these two factors. The technical terms may not be in our mouths, but we discuss this instance or that of the question in point almost every day of our lives. One part of the business of philosophy and of science is not only to answer questions but to ask them correctly. This question is always wrongly asked, and therefore cannot be answered, or is incorrectly answered. We persist in using the mathematical idea of addition, and we seek to show that, say, seventy per cent. of the result is due to the innate factor and thirty per cent. to the acquired. But the truth is that so long as we begin with this idea we may prove what we please. If we keep our attention fixed upon the environmental or educational factor we can easily and correctly demonstrate that in certain circumstances Mozart would have been tone-deaf and Shakespeare a gibbering idiot--hence, but incorrectly, we argue that environment is practically everything. _Per contra_, we can easily and correctly demonstrate that no education in the world could enable a door-mat or a cabbage or ourselves to write _Don Giovanni_ or _Hamlet_--hence, but incorrectly, we argue that the material to be operated upon is everything. We have to learn, however, that the analogy _is one not of addition but of multiplication_. Neither inheritance nor environment, as such, gives anything. The environmental factor may be potentially one hundred--an ideal education--but the innate or inherited factor may be nothing, as when the pupil is a door-mat or a fool. The result then is nothing. Darwin had the trombone played to a plant, but he did not make a Palestrina. No academy of music will make a beetroot into a Beethoven, though I dare say a well-trained beetroot might write a musical comedy. The point is that one hundred multiplied by nothing equals nothing. Similarly, the innate factor may be one hundred, as in the case of a potential genius, but he may be brought up upon alcohol and curses amongst savages, and the result again is nothing. Keep the idea of multiplication in the mind, and the facts are seen rightly. No matter how big either factor be, if it be multiplied by nothing it yields nothing, or if it be multiplied by a fraction, as in the ordinary education of a genius, it yields less than it should. But in this controversy people persist in assuming that inheritance or education gives definitely so much which is there anyhow, whereas, really, it only supplies a potential figure, which may realise infinity or nothing, according to what it is multiplied by. With all deference, I