‘In attempting to throw some light on these abstruse subjects, I wish to preserve the due mean between confidence and despair. But whether I have any success in this attempt or not, I shall always avow myself your disciple in metaphysics. I have learned more from your writings in this kind than from all others put together. Your system appears to me not only coherent in all its parts, but likewise justly deduced from principles commonly received among philosophers,—principles which I never thought of calling in question, until the conclusions you draw from them in the _Treatise of Human Nature_ made me suspect them. If these principles are solid your system must stand; and whether they are or not can better be judged after you have brought to light the whole system that grows out of them, than when the greater part of it was wrapped up in clouds and darkness. I agree with you therefore, that if this system shall ever be demolished, you have a just claim to a great share of the praise, both because you have made it a distinct and determinate mark to be aimed at, and have furnished proper artillery for the purpose. When you have seen the whole of my performance, I shall take it as a very great favour to have your opinion upon it, from which I make no doubt of receiving light, whether I receive conviction or no.’ Hume’s philosophy being the suicide of intelligence, can hardly be spoken of as a ‘system.’ It is not constructive, but wholly destructive, and therefore a negation of system, philosophic or other, in a finally speechless and motionless agnostic doubt. Hume’s letter to Reid was his only rejoinder to the _Inquiry_. In 1763 he had ceased to produce philosophical books. His recognition of the ‘deeply philosophical’ nature of Reid’s argument is a testimony to the worth of the work on which Reid’s literary reputation chiefly rests. The ‘share of the praise’ which Hume claims, Reid was ready to concede. ‘I hope,’ he says in the Dedication of the _Inquiry_, ‘I hope that the author of this sceptical system wrote it in the belief that it would be useful to mankind. And perhaps it may prove so at last. For I conceive the sceptical writers to be a set of men whose business it is to pick holes in the fabric of knowledge wherever it is weak and faulty; and when those places are properly repaired, the whole building becomes more firm and solid than it was formerly’. And, in fact, the intellectual progress of mankind has been sustained by an alternation of sceptical and conservative philosophies.