are always involved in any actual activity. it is not, i think, making too much of it to call them two sorts of knowledge, because (though in fact they do not exist separately) there are certain important differences between them. the first sort of knowledge i will call technical knowledge or knowledge of technique. in every art and science, and in every practical activity, a technique is involved. in many activities this technical knowledge is formulated into rules which are, or may be, deliberately learned, remembered, and, as we say, put into practice; but whether or not it is, or has been, precisely formulated, its chief characteristic is that it 