“How the human mind when it reasons concerning the general nature of triangles, should either conceive, as Mr. Locke imagines it does, the idea of a triangle, which is neither obtusangular, nor rectangular, nor acutangular; but which was at once both none and of all those together; or should, as Malbranche thinks necessary for this purpose, comprehend at once, within its finite capacity, all possible triangles of all possible forms and dimensions, which are infinite in number, is a question to which it is not easy to give a satisfactory answer.” He suggests that notions like those of Plato, or Cudworth, or Malebranche, depend a good deal upon the vague and general language in which they are expressed. So long as a philosophy is not very distinctly explained, it “passes easily enough through the indolent imagination accustomed to substitute words in the room of ideas.” Platonism vanishes indeed, and is discovered to be altogether incomprehensible upon an attentive consideration. It did, however, require attentive consideration, and but for Aristotle “might without examination have continued to be the current philosophy for a century or two.” This early and unnoticed composition proves that Smith had thought deeply on metaphysics though he deliberately avoided them in his masterpieces. He found time to translate and read part of the essay as a Latin dissertation; but his engagements in Edinburgh prevented him from taking up his new work before the autumn. When October came he found his task doubled. Craigie, the Professor of Ethics, had fallen ill, and had been ordered to Lisbon for his health. Smith was informed of this by Dr. Cullen, one of his new colleagues, and was requested to undertake Craigie’s duties. It was further suggested that he should pay particular attention to jurisprudence and politics, which were held to fall within the province of moral philosophy. Smith replies (3rd September 1751) that he will gladly relieve Craigie of his class, and will willingly undertake to lecture on natural jurisprudence and politics.