In recent years, one significant component of earlier philosophical discussion—what used to be called "moral psychology"—has fallen into unjustified neglect. Yet, to the extent that motives are of crucial importance to ethics, the philosophical analysis of talk about "motivation" can play a helpful part in showing how values achieve practical expression in actual conduct; and this remains true even where, on the face of it, the activities in question are as "purely intellectual" as those of the natural sciences. So, in the present chapter, I shall be raising questions about the personal engagement in sciences of scientists as human individuals.