So that though our visible ideas resemble in miniature the outline of the figure of coloured bodies, in other respects they serve only as a language, which by acquired associations introduce the tangible ideas of bodies. Hence it is, that this sense is so readily deceived by the art of the painter to our amusement and instruction. The reader will find much very curious knowledge on this subject in Bishop Berkeley's Essay on Vision, a work of great ingenuity.] "HENCE in Life's portico starts young Surprise With step retreating, and expanded eyes; The virgin, Novelty, whose radiant train Soars o'er the clouds, or sinks beneath the main, With sweetly-mutable seductive charms Thrills the young sense, the tender heart alarms. 150 Then Curiosity with tracing hands And meeting lips the lines of form demands, Buoy'd on light step, o'er ocean, earth, and sky, Rolls the bright mirror of her restless eye. While in wild groups tumultuous Passions stand, And Lust and Hunger head the Motley band; Then Love and Rage succeed, and Hope and Fear; And nameless Vices close the gloomy rear; Or young Philanthropy with voice divine Convokes the adoring Youth to Virtue's shrine; 160 Who with raised eye and pointing finger leads To truths celestial, and immortal deeds. [Footnote: _Starts young Surprise_, l. 145. Surprise is occasioned by the sudden interruption of the usual trains of our ideas by any violent stimulus from external objects, as from the unexpected discharge of a pistol, and hence does not exist in our dreams, because our external senses are closed or inirritable. The fetus in the womb must experience many sensations, as of resistance, figure, fluidity, warmth, motion, rest, exertion, taste; and must consequently possess trains both of waking and sleeping ideas. Surprise must therefore be strongly excited at its nativity, as those trains of ideas must instantly be dissevered by the sudden and violent sensations occasioned by the dry and cold atmosphere, the hardness of external bodies, light, sound, and odours; which are accompanied with pleasure or pain according to their quantity or intensity. As some of these sensations become familiar by repetition, other objects not previously attended to present themselves, and produce the idea of novelty, which is a less degree of surprise, and like that is not perceived in our dreams, though for another reason; because in sleep we possess no voluntary power to compare our trains of ideas with our previous knowledge of nature, and do not therefore perceive their difference by intuitive analogy from what usually occurs.