is possible? I can distinctly conceive it, say you; therefore it is possible. I do not admit this argument. May not a man who is a mathematician as distinctly conceive that in the infinite variety of numbers gradually ascending, there is no ratio whatsoever which is not equal to the ratio of some one whole number to some other whole number? Yet the mathematician can demonstrate that there are innumerable ratios which are not equal to the ratio of some one number to another. Many mathematicians, taking it for granted that it was possible to square the circle, have spent their lives in a fruitless pursuit. May not our taking things to be possible, in matters of higher moment, when we can show no good reason that they are so, lead us into unnecessary disputes and vain theories? Ought we to admit that as a just argument in reasoning, or even as a pressing difficulty, which is grounded on the supposition that such a thing is possible, when in reality we have no good evidence of its being possible, and for anything we can show to the contrary, it may be impossible?'
A letter to Dr. Gregory in March 1786 shows the Essays on the Active or Moral Powers in the press:—'I am proud of the approbation you express of the Essays. I have made some corrections and additions, but such as I hope will not make it necessary to write the book over again. But I wish, if I find health and leisure in summer, to add some Essays to go before that on “Liberty of the Will,” in order to give some further elucidation of the principles of morals. I expect your remarks and D. Stewart’s on what is in hand. It will be no inconvenience to wait two, three, or even four months.' Two years later, early in 1788, when he was in his seventy-eighth year, the five Essays on the Active Powers of Man were published. This was Reid's last appearance as a philosophical author. The eight Essays of 1785, and the five Essays of 1788, all relate to human Power—power immanent or intellectual, and power overtly operative or moral.
