As he advanced, however, his manner became warm and animated, and his expression easy and fluent.  On points susceptible of controversy you could easily discern that he secretly conceived an opposition to his opinions, and that he was led upon this account to support them with greater energy and vehemence.  By the fulness and variety of his illustrations the subject gradually swelled in his hands and acquired a dimension which, without a tedious repetition of the same views, was calculated to seize the attention of his audience, and to afford them pleasure as well as instruction in following the same subject through all the diversity of shades and aspects in which it was presented, and afterwards in tracing it backwards to that original proposition or general truth from which this beautiful train of speculation had proceeded."[44]

One little peculiarity in his manner of lecturing was mentioned to the late Archdeacon Sinclair by Archibald Alison the elder, apparently as Alison heard it from Smith’s own lips.  He used to acknowledge that in lecturing he was more dependent than most professors on the sympathy of his hearers, and he would sometimes select one of his students, who had more mobile and expressive features than the rest, as an unsuspecting gauge of the extent to which he carried with him the intelligence and interest of the class.  “During one whole session,” he said, “a certain student with a plain but expressive countenance was of great use to me in judging of my success.  He sat conspicuously in front of a pillar:  I had him constantly under my eye.  If he leant forward to listen all was right, and I knew that I had the ear of my class; but if he leant back in an attitude of listlessness I felt at once that all was wrong, and that I must change either the subject or the style of my address."[45]

The great majority of his students were young men preparing for the Presbyterian ministry, a large contingent of them—­quite a third of the whole—­being Irish dissenters who were unfairly excluded from the university of their own country, but appear to have been no very worthy accession to the University of Glasgow.  We know of no word of complaint against them from Smith, but they were a sore trial both to Hutcheson and to Reid.  Reid says he always felt in lecturing to those “stupid Irish teagues” as St. Anthony must have felt when he preached to the fishes,[46] and Hutcheson writes a friend in the north of Ireland that his Irish students were far above taking any interest in their work, and that although he had “five or six young gentlemen from Edinburgh, men of fortune and fine genius, studying law, these Irishmen thought them poor bookworms."[47] Smith had probably even more of this stamp of law students than Hutcheson.  Henry Erskine attended his class on jurisprudence as well as his elder brother.  Boswell was there in 1759, and was made very proud by the certificate he received from his professor at the close of the session, stating that he, Mr.