To mention the particular beauties of the essay would be unprofitably tedious; but I cannot forbear to observe, that the comparison of a student's progress in the sciences with the journey of a traveller in the Alps, is, perhaps, the best that English poetry can show. A simile, to be perfect, must both illustrate and ennoble the subject; must show it to the understanding in a clearer view, and display it to the fancy with greater dignity; but either of these qualities may be sufficient to recommend it. In didactick poetry, of which the great purpose is instruction, a simile may be praised which illustrates, though it does not ennoble; in heroicks, that may be admitted which ennobles, though it does not illustrate. That it may be complete, it is required to exhibit, independently of its references, a pleasing image; for a simile is said to be a short episode. To this antiquity was so attentive, that circumstances were sometimes added, which, having no parallels, served only to fill the imagination, and produced what Perrault ludicrously called "comparisons with a long tail." In their similes the greatest writers have sometimes failed; the ship-race, compared with the chariot-race, is neither illustrated nor aggrandized; land and water make all the difference: when Apollo, running after Daphne, is likened to a greyhound chasing a hare, there is nothing gained; the ideas of pursuit and flight are too plain to be made plainer, and a god and the daughter of a god are not represented much to their advantage by a hare and dog. The simile of the Alps has no useless parts, yet affords a striking picture by itself; it makes the foregoing position better understood, and enables it to take faster hold on the attention; it assists the apprehension, and elevates the fancy. Let me, likewise, dwell a little on the celebrated paragraph, in which it is directed that "the sound should seem an echo to the sense;" a precept which Pope is allowed to have observed beyond any other English poet.