T 2.3.10.6

It may indeed be objected, that such a remote sympathy is a very slight foundation for a passion, and that so much industry and application, as we frequently observe in philosophers, can never be deriv'd from so inconsiderable an original. But here I return to what I have already remark'd, that the pleasure of study consists chiefly in the action of the |mind, and the exercise of the genius and understanding in the discovery or comprehension of any truth. If the importance of the truth be requisite to compleat the pleasure, 'tis not on account of any considerable addition, which of itself it brings to our enjoyment, but only because 'tis, in some measure, requisite to fix our attention. When we are careless and inattentive, the same action of the understanding has no effect upon us, nor is able to convey any of that satisfaction, which arises from it, when we are in another disposition.