From James Boswell’s Life of Johnson (pg. 57 of vol.1 of the 6 volume Oxford text edited by Hill and Powell).
In estimating the progress of his mind during these two years, as well as in future periods of his life, we must not regard his own hasty confession of idleness; for we see, when he explains himself, that he was acquiring various stores; and, indeed he himself concluded the account with saying, ‘I would not have you think I was doing nothing then.’ He might, perhaps, have studied more assiduously; but it may be doubted whether such a mind as his was not more enriched by roaming at large in the fields of literature than if it had been confined to any single spot. The analogy between body and mind is very general, and the parallel will hold as to their food, as well as any other particular. The flesh of animals who feed excursively, is allowed to have a higher flavour than that of those who are cooped up. May there not be the same difference between men who read as their taste prompts and men who are confined in cells and colleges to stated tasks?