Thus, also, with hearing. We consider the sonorous body as the cause; but the sensation is produced through the medium of the air, which affects the drum of the ear. But in the case of taste and touch, the body which is regarded by the mind as the cause must come in contact with the nerves of the tongue or the body to produce the sensation. _Smell._ The sense of smell is one which greatly conduces to the preservation, the comfort, and the happiness of man. It is a continual aid to him in detecting polluted atmosphere or unhealthy food. The direct enjoyment it affords is probably less in amount than that derived from any of the other senses; yet, were we deprived of all the enjoyment gained through this source, we should probably find the privation much greater than we at first might imagine. When we walk forth among the beauties of nature, the fresh perfumes that send forth their incense are sources both of immediate and succeeding gratification. The beautiful images of nature which rise to the mind in our imaginative hours, would lose many of their obscure but charming associations were the fields stripped of the fragrance of their greens and the flowers of their sweet perfumes. Nature would appear to have lost that moving spirit of life which now ever rides upon the evening zephyrs and the summer breeze. As it is, as we walk abroad, all nature seems to send forth its welcome, while to its Maker's praise "Each odorous leaf, Each opening blossom, freely breathes abroad Its gratitude, and thanks Him with its sweets." _Taste._ When a sapid body is applied to the organ of taste, two sensations are produced, one of _touch_ and one of _taste_. We are conscious of the difference of these sensations when we apply a body to the tongue which has taste, and then immediately one which has not. It is probable, however, that the same set of nerves serve both purposes. It is one of the numberless evidences of the benevolence of our Creator that the process which is necessary for the preservation of life, and which depends upon the voluntary activity of every human being, should be connected with a sense which affords such gratification that the duty is sought as a pleasure. Were mankind led to seek food merely in the exercise of reason for the purpose of preserving life, multitudes, through carelessness and forgetfulness, would be perpetually neglecting that regular supply without which the animal system would become deranged and enfeebled. By the present constitution of the body, the gratification of this sense is an object of desire, and thus we are continually reminded of our duty, and led to it as a source of enjoyment.