In discussing senses of is I have allowed more than a little 346 which would have no proper place in an elementary Logic course to intrude; and thus illustrated the worst risk in the ven­ ture. You cannot defend a subject against philosophy without turning philosopher, any more than you can put down violence without using force. In this chapter the risk is greater. The way to meet it is to acknowledge it, study it and limit it. What I am noting down here are, at best, only the materials of a possible teaching subject. What should be considered early is still entwined with what should be considered late, if at all. But the separation must proceed by steps and any step here is better than none.