We see the key to Napoleon's successes in the quality of his mind at the time of those successes, and we see the key to his failures in a lowering of the quality of that mind. Military writers tell us that his mind was not of the same quality when he planned his Russian campaign as it had been when he planned his early campaigns. Now the reasoning faculties do not grow dull when one approaches middle age; but the imaginative faculties do--(in most people). It is an old saying that "one cannot teach an old dog new tricks." Clearly, this cannot be because of any failing of memory, though memory fails with age; because the memory is not involved, save slightly. It must be therefore because of failing impressionability and receptivity. We all speak of the "receptive years," meaning the years of childhood and then of youth; and it is a common saying that young people are more receptive than old people. Of what are they receptive? Clearly, of mental impressions. Parents and teachers are warned not to forget that the minds of young people are very impressionable, and to be careful that their minds receive good impressions only, so far as they can compass it. Napoleon, when he made his Russian campaign, was only 43 years old in years; but he had lived a life that was far from normal or hygienic physically, and extremely abnormal and unhygienic mentally. The intention of the last sentence is to point out that mental health cannot be long preserved amid surroundings mentally unhealthful, any more than physical health can be long preserved amid surroundings physically unhealthful; and that the highest qualities of our nature are the most difficult to maintain and therefore are the first to fail, under unhealthful surroundings. The spiritual faculties fail first, then the moral, then the mental and lastly the physical. Now the imagination, while a mental quality, rather than a moral one, partakes in a measure of the spiritual, and is one of the highest of the mental attributes. For this reason imagination is one of the first to be impaired. The especial picture of the imagination that becomes faulty under certain conditions, is the picture of one's self. Under conditions such as Napoleon had lived under for several years, the picture of himself in his mind had become unduly magnified in relation to the pictures of other men. Now is there any one thing more dangerous to a man than to carry in his mind an incorrect picture of himself?