In considering his critical gift, it is well to distinguish those two elements of acute perception and sober judgment which I have already specified, for he possessed the former in larger measure than the latter. The same activity of mind which made him notice everything while travelling or entering a company of strangers, played incessantly upon the historical data of his work, and supplied him with endless theories as to the meaning of a statement, the source it came from, the way it had been transmitted, the conditions under which it was made. No one could be more acute and penetrating in what the Germans call _Quellenforschung_, the collection and investigation and testing of the sources of history, nor could any one be more painstaking. Errors of view, apart from those trivial inaccuracies already referred to, did not arise from an indolence that left any stone unturned, but rather from an occupation with the leading idea which had drawn his attention away from the details of time and place. The ingenuity with which he built up theories was as admirable as the art with which he stated them. People whom that art fascinated sometimes fancied that the charm lay entirely in the style. But the style was only a part of the craftsmanship. The facility in theorising, the power of grouping facts under new aspects, the skill in gathering and sifting evidence, were as remarkable as those artistic qualities which expressed themselves in the paragraphs and sentences and phrases. What danger there was arose from this fecundity. His mind was so fertile, could see so much in a theory and apply it so dexterously, that his judgment was sometimes dazzled by the brilliance of his ingenuity. I do not think he loved his theories specially because they were his own, for he often modified them, and was ready to consider any one else's suggestions; but he had a passion for light, and when a new view seemed to him to explain things previously dark, he wanted the patience to suspend his judgment and abide in uncertainty. Some of his hypotheses he himself dropped. Some others he probably would have dropped, as the authorities he respected have not embraced them. Others have made their way into general acceptance, and may become still more useful as future research works them out. But, whether right or wrong, they were instructive. Every one of them is based upon facts whose importance had not been so fully seen before, and suggests a point of view worth considering. Green's view may sometimes appear fanciful: it is never foolish, or superficial, or perverse. And so far from being credulous, his natural tendency was towards doubt.