'Almost every one knows Lord Mansfield's advice to a man of practical good sense, who, being appointed governor of a colony, had to preside in its court of justice, without previous judicial practice or legal education. The advice was to give his decision boldly, for it would probably be right; but never to venture on assigning reasons, for they would almost infallibly be wrong. In cases like this, which are of no uncommon occurrence, it would be absurd to suppose that the bad reason was the source of the good decision. Lord Mansfield knew that if any reason were assigned it would be necessarily an afterthought, the judge being _in fact_ guided by impressions from past experience, without the circuitous process of framing general principles from them, and that if he attempted to frame any such he would assuredly fail. Lord Mansfield, however, would not have doubted that a man of equal experience, who had also a mind stored with general propositions derived by legitimate induction from that experience, would have been greatly preferable as a judge, to one, however sagacious, who could not be trusted with the explanation and justification of his own judgments. The cases of able men performing wonderful things they know not how, are examples of the less civilised and most spontaneous form of the operations of superior minds It is a _defect in them_, and _often a source of errors_, not to have generalised as they went on; but generalisation is a help, the most important indeed of all helps, yet not an essential.'* * Mill's Logic, pp. 251-5. In illustration of generalising from single instances, Miss Martineau gives this example:--'A raw Chinese traveller in England was landed by a Thames waterman who had a wooden leg. The stranger saw that the wooden leg was used to stand in the water with, while the other was high and dry. The apparent economy of the fact struck the Chinese; he saw in it strong evidence of design, and wrote home that in England one-legged men are kept for watermen, to the saving of all injury to health, shoe, and stocking, from standing in the river.'* Reasoning on insufficient data-- Falls like an inverted cone, Wanting its proper base to stand upon.