When Stewart was obliged by infirmity to retire from the active discharge of his duties, he was succeeded by Thomas Brown (1778-1820). Brown had shown early precocity, and at the age of fifteen had attracted Stewart's notice by some remarks on a psychological point. He published at twenty a criticism of Darwin's _Zoonomia_, and he became one of the _Edinburgh Review_ circle. When the _Review_ was started he contributed an article upon Kant. In those happy days it was so far from necessary to prepare oneself for such a task by studying a library of commentators that the young reviewer could frankly admit his whole knowledge to be derived from Villers' _Philosophie de Kant_ (1801).[466] Soon afterwards he took an important share in a once famous controversy. John Leslie, just elected to the mathematical chair at Edinburgh, was accused of having written favourably of Hume's theory of causation. Whigs and Tories took this up as a party question,[467] and Brown undertook to explain in a pamphlet what Hume's theory was, and to show that it did not lead to atheism. Leslie's friends triumphed, though it does not appear how far Brown's arguments contributed to their success. The pamphlet was rewritten and enlarged, and a third edition of 1818 gives a full exposition of his theory. Brown had meanwhile become Stewart's leading disciple, and in 1810 was elected to be his colleague. Brown held the position, doing all the active duties, until his premature death in 1820. Brown, according to his biographer, wrote his lectures immediately before delivery, and completed them during his first two years of office. His theories, as well as his words, were often, according to the same authority, extemporised. Brown found that he could not improve what he had written under 'very powerful excitement.' Moreover, he had an unlucky belief that he was a poet. From 1814 till 1819 he brought out yearly what he supposed to be a poem. These productions, the _Paradise of Coquets_ and the rest, are in the old-fashioned taste, and have long passed into oblivion.
The lectures, published posthumously, became a text-book for students, and reached a nineteenth edition in 1851. Their faults, considered as philosophical treatises, are palpable. They have the wordiness of hasty composition, and the discursive rhetoric intended to catch the attention of an indolent audience. Brown does not see that he is insulting his hearers when he apologises for introducing logic into lectures upon metaphysics, and indemnifies them by quotations from Akenside and the _Essay on Man_. Brown, however, showed great acuteness and originality. He made deviations, and took pains to mark his deviations, from Reid, though he spoke more guardedly of his own friend, Stewart. Stewart, who had strongly supported Brown's election, was shocked when, on the publication of the lectures, he came to discover that his colleague had been preaching heresy, and wrote with obvious annoyance of Brown's hastiness and dangerous concessions to the enemy.[468] Brown, however, impressed his contemporaries by his ability. Sydney Smith is probably reporting the current judgment of his own circle when he says[469] that in metaphysics Stewart was a 'humbug' compared with Brown. I certainly think that Stewart, whom I should be sorry to call a humbug, shows less vigour and subtlety. Brown, at any rate, impressed both the Mills, and his relation to them is significant.