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 derived from so inconsiderable an original. But here I return to what I have already remarked, 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 complete 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. But beside the action of the mind, which is the principal foundation of the pleasure, there is likewise required a degree of success in the attainment of the end, or the discovery of that truth we examine. Upon this head I shall make a general remark, which may be useful on many occasions, viz. that where the mind pursues any end with passion, though that passion be not derived originally from the end, but merely from the action and pursuit, yet, by the natural course of the affections, we acquire a concern for the end itself, and are uneasy under any disappointment we meet with in the pursuit of it. This proceeds from the relation and parallel direction of the passions above-mentioned.