On the other hand, though Erasmus Darwin defined a fool to his friend Edgeworth as 'a man who never tried an experiment in his life,' he was wanting himself in the rigorous and patient inductive habit which so strikingly distinguished his grandson Charles. That trait, as we shall presently see, the biological chief of the nineteenth century derived in all probability from another root of his genealogical tree. Erasmus Darwin gave us brilliant suggestions rather than cumulative proof: he apologised in his 'Zoonomia' for 'many conjectures not supported by accurate investigation or conclusive experiments,' Such an apology would have been simply impossible to the painstaking spirit of his grandson Charles. Erasmus Darwin was twice married. His first wife was Mary, daughter of Mr. Charles Howard, of Lichfield, and it was her son, Robert Waring Darwin, who became the father of our hero, Charles. It is fashionable to say, in this and sundry other like cases, that the mental energy skips a generation. People have said so in the case of that intermediate Mendelssohn who was son of Moses Mendelssohn, the philosopher, and father of Felix Bartholdy Mendelssohn, the composer--that mere link in a marvellous chain who was wont to observe of himself in the decline of life, that in his youth he was called the son of the great Mendelssohn, and in his old age the father of the great Mendelssohn. As a matter of fact, one may fairly doubt whether such a case of actual skipping is ever possible in the nature of things. In the particular instance of Robert Waring Darwin at least we may be pretty sure that the distinctive Darwinian strain of genius lay merely latent rather than dormant: that it did not display itself to the world at large, but that it persisted silently as powerful as ever within the remote recesses of the thinking organism. Not every man brings out before men all that is within him. Robert Waring Darwin was a physician at Shrewsbury; and he attained at least sufficient scientific eminence in his own time to become a Fellow of the Royal Society, in days when that honour was certainly not readily conferred upon country doctors of modest reputation. Charles Darwin says of him plainly, 'He was incomparably the most acute observer whom I ever knew.' It may well have been that Robert Darwin lived and died, as his famous son lived for fifty years of his great life, in comparative silence and learned retirement; for we must never forget that if Charles Darwin had only completed the first half century of his laborious existence, he would have been remembered merely as the author of an entertaining work on the voyage of the 'Beagle,' a plausible theory of coral islands, and a learned monograph on the fossil barnacles. During all those years, in fact, he had really done little else than collect material for the work of his lifetime. If we judge men by outward performance only, we may often be greatly mistaken in our estimates: