Late hours, irregular habits, and want of attention to diet, are common errors with most young men, and these gradually, but at first imperceptibly, undermine the health, and lay the foundation for various forms of disease in after life. It is a very difficult thing to make young persons comprehend this. They frequently sit up as late as twelve, one, or two o'clock, without experiencing any ill effects; they go without a meal to-day, and to-morrow eat to repletion, with only temporary inconvenience. One night they will sleep three or four hours, and the next nine or ten; or one night, in their eagerness to get away into some agreeable company, they will take no food at all; and the next, perhaps, will eat a hearty supper, and go to bed upon it. These, with various other irregularities, are common to the majority of young men, and are, as just stated, the cause of much bad health in mature life. Indeed, nearly all the shattered constitutions with which too many are cursed, are the result of a disregard to the plainest precepts of health in early