Another parallel here occurs between Reid and Kant. The _Kritik of Pure Reason_, Kant’s first great work, appeared in 1781, when he was in his fifty-seventh year. So, too, with Locke, who inaugurated the era of modern thought in which Reid and Kant are chief figures. His _Essay_, like Reid’s _Inquiry_, was the first fruit of twenty years of reflective thought, and it too made its appearance when its author was in his fifty-seventh year. It is curious to contrast the balanced caution and moderation of these long pondered treatises with the more paradoxical productions of others, whose intellectual ardour and impatience speedily committed them to all-comprehensive systems. Descartes, at forty, with his provisional doubt and reconstruction on a slender foundation; Spinoza, younger still, with his rational evolution of the universe from a single substance; Berkeley with his analysis of the material world into significant ideas, delivered at the age of twenty-five with the impetuous enthusiasm of Irish juvenile genius; and David Hume with his universal disintegration of human knowledge and belief, planned before he was one-and-twenty, composed before he was twenty-five, and eagerly given to the world in his twenty-eighth year. Reid, with his ‘good and well-wearing parts,’ characteristically represents the restrained authorship of those who treat our short life on this planet as short enough for well-weighed answers to the final questions about life and the universe. As Reid’s _Inquiry_ was really an appeal to human nature in arrest of Hume’s intellectual suicide, he desired, before presenting it to the world, to submit the argument privately to the Edinburgh sceptic. This was done through their common friend Dr. Blair. After Hume had read portions of the manuscript, he wrote this courteous letter to Reid on Feb. 25, 1763:—