'But what is Error?' continues the preacher; and the Solitary replies by saying, 'somewhat haughtily,' that love, admiration, and hope are 'mad fancy's favourite vassals.' The distinction between fancy and imagination is, in brief, that fancy deals with the superficial resemblances, and imagination with the deeper truths which underlie them. The purpose, then, of the 'Excursion,' and of Wordsworth's poetry in general, is to show how the higher faculty reveals a harmony which we overlook when, with the Solitary, we Skim along the surfaces of things. The rightly prepared mind can recognise the divine harmony which underlies all apparent disorder. The universe is to its perceptions like the shell whose murmur in a child's ear seems to express a mysterious union with the sea. But the mind must be rightly prepared. Everything depends upon the point of view. One man, as he says in an elaborate figure, looking upon a series of ridges in spring from their northern side, sees a waste of snow, and from the south a continuous expanse of green. That view, we must take it, is the right one which is illuminated by the 'ray divine.' But we must train our eyes to recognise its splendour; and the final answer to the Solitary is therefore embodied in a series of narratives, showing by example how our spiritual vision may be purified or obscured. Our philosophy must be finally based, not upon abstract speculation and metaphysical arguments, but on the diffused consciousness of the healthy mind. As Butler sees the universe by the light of conscience, Wordsworth sees it through the wider emotions of awe, reverence, and love, produced in a sound nature. The pantheistic conception, in short, leads to an unsatisfactory optimism in the general view of nature, and to an equal tolerance of all passions as equally 'natural.' To escape from this difficulty we must establish some more discriminative mode of interpreting nature. Man is the instrument played upon by all impulses, good or bad. The music which results may be harmonious or discordant. When the instrument is in tune, the music will be perfect; but when is it in tune, and how are we to know that it is in tune? That problem once solved, we can tell which are the authentic utterances and which are the accidental discords. And by solving it, or by saying what is the right constitution of human beings, we shall discover which is the true philosophy of the universe, and what are the dictates of a sound moral sense. Wordsworth implicitly answers the question by explaining, in his favourite phrase, how we are to build up our moral being.