Some may wonder at such a history of an unknown trouble,--some who, when anything harasses them, mount a horse, and gallop over the sea-sands or the race-course, or visit their friends or the theatre, or resort to music, or romp with children. Let them remember that we cannot do these things,--that the very weakness which subjects us to these troubles, forbids our escape from them. We know, as well as they, that if once we could feel the open air upon our brows, our feet on the grass, our bodies in exercise and vigour, all would be well with us; but, as we cannot use these remedies, the knowledge is of no immediate avail. If we can get to the window and look abroad, that is well, as far as it goes; but we are most subject to our tyrant in the night, and in midwinter,--at times when we cannot look abroad; and it may even happen, too, that the tyrant dims the sun at noon-day, and blots out the landscape, or renders us blind to it. What then is to be done? We evade the misery, when we can, by stirring books, (the most objective that can be had), or by seeing what we can of the world by the telescope, or by resorting to some sweet familiar spring of poetry; but this last expedient is impaired by the fear of mixing painful associations with pleasures too sacred and dear to be endangered. Or we defy the foe in reckless anguish, or we endure in silent patience. But there is something far better to be done,--not always; but still, not seldom. We can turn the forces of ideas against themselves--meet them with their own weapons. We can call in the power of an idea to overcome the tyranny of another idea; and then we come off conquerors, and with a soul-felt joy.