132 JOHN PLAYPAIR.
hover round their former mansions, inspiring their worthy successor with the love of wisdom, and pointing out the road to immortality."
From his thirst after knowledge being untainted by political or local preju- dices, Playfair had early turned himself to the important discoveries of the continental algebraists, and was the first man of eminence to introduce them to British notice. He perceived the pi'ejudices entertained on the subject in Eng- land, and probably the discovery sharpened his appetite for a subject i-.liirh he found was almost untouched. Speaking of Dr Maskelyne, he says, " Le is much attached to the study of geometry, and I am not sure that he is very deep- ly versed in the late discoveries of the foreign algebraists. Indeed, this seems to be somewhat the case with all the English mathematicians : they despise their brethren on the continent, and think that everything great in science must be for ever confined to the country that produced Sir Isaac Newton." In the works of an eminent natural philosopher one may search long before he will find any- thing which shows in explicit terms the exact discipline of mind or system of reasoning, by which he has made it to happen that all he has said, has so much the appearance of being truth ; but a petty remark, disconnected with the ordi- nary pursuits of the philosopher, may often strikingly illustrate the operation of his mind, and the means by which he has disciplined himself to approach as near as possible to truth ; and, such a passage occurring in this short diary, we beg to insert it. " An anecdote of some Indians was told, that struck me very much, as holding up but too exact a picture of many of our theories and rea- sonings from analogy. Some American savages having experienced the effects of gunpowder, and having also accidentally become masters of a small quantity of it, set themselves to examine it, with a design of finding out what was its nature, and how it Avas to be procured. The oldest and wisest of the tribe, after considering it attentively, pronounced it to be a seed. A piece of ground was accordingly prepared for it, and it was sown in the fullest confidence that a great crop of it was to be produced. We smile at the mistake of these In- dians, and we do not consider, that, for the extent of their experience, they reasoned well, and drew as logical a conclusion as many of the philosophers of Europe. Whenever we reason only from analogy and resemblance, and when- ever we attempt to measure the nature of things by our conceptions, we are precisely in the situation of these poor Americans." In this Playfair exempli- fied the propensity to reason from certain qualities perceived to be identical, when it is not known but that other qualities not perceived, may be at variance. The wise American saw colour and form like those of a seed, and from these he drew his conclusion. Had he been a botanist, he would have discovered that the grain consisted of saltpetre and charcoal, instead of kernel ; and, whatever else he could have made of it, he would have quickly perceived that it was not a seed. In connexion with this it is to be held in mind, that Playfair was es- sentially a reasoner, and that he was more celebrated for separating the true from the false in the writings of others, or for establishing and applying truths accidentally stumbled upon by others, than for extensive discoveries of his own.
In 1785, Dr Adam Ferguson exchanged the moral chair in the university for that of mathematics, taught by professor Dugald Stewart, and, being in bad health, chose Playfair as his assistant. He continued, however, to attend his two pupils until' 1787, when he took up his residence with his mother, who had for some time lived in Edinburgh. He now commenced a series of papers which appeared in the Transactions of the Royal Society of Edinburgh. The first of these was the life of Dr Matthew Stewart, the late professor of mathe-