_Prevalence at different Periods of Life._--There are those, of fortunate temperament, with whom this seems to be the prevailing disposition, to whom every thing wears a cheerful and sunny aspect. Of others, the reverse is true. In early life this habitual joyousness of spirit is more commonly prevalent; in advanced years, more rarely met with. Whether it be that age has chilled the blood, or that the sober experience of life has saddened the heart, and corrected the more romantic visions of earlier years, as life passes on we are less habitually under the influence of this disposition. It is no longer the prevailing frame of the mind. In the beautiful language of another, "We are not happy, without knowing why we are happy, and though we may still be susceptible of joy, perhaps as intense, or even more intense, than in our years of unreflecting merriment, our joy must arise from a cause of corresponding importance; yet even down to the close of extreme old age there still recur occasionally some gleams of this almost instinctive happiness, like a vision of other years, or like those brilliant and unexpected corruscations which sometimes flash along the midnight of a wintry sky, and of which we are too ignorant of the circumstances that produce them, to know when to predict their return." _The opposite Feeling._--Corresponding to this general state of mind now described, is one of quite the opposite character--that habitual disposition to sadness which is usually called melancholy. Like its opposite, cheerfulness, it is rather a frame of mind than a positive emotion, and, like its opposite, it exists, often, without any marked and definite cause to which we can attribute it. It is that state in which subsiding grief, or the pressure of any severe calamity now passing away, leaves the mind, the grey and solemn twilight that succeeds a partial or total eclipse. It is, with many persons, the habitual state of mind, through long periods, perhaps even the greater part, of life. Not unfrequently it occurs that minds, of the rarest genius and most delicate sensibility, are subject to that extreme and habitual depression of spirits which casts a deep gloom over the brightest objects, and renders life itself a burden. This state of habitual gloom and despondency, itself usually a form of disease, the result of some physical derangement, deepens sometimes into a fixed and permanent disorder of the mind, and constitutes one of the most pitiable and hopeless forms of insanity. Such was the case with the melancholy, but most amiable and gentle Cowper.