But if now our perception were constantly bound to the real present of things, its material would be entirely under the dominion of chance, which seldom produces things at the right time, seldom arranges them for an end and for the most part presents them to us in very defective examples. Therefore the _imagination_ is required in order to complete, arrange, give the finishing touches to, retain, and repeat at pleasure all those significant pictures of life, according as the aims of a profoundly penetrating knowledge and of the significant work whereby they are to be communicated may demand. Upon this rests the high value of imagination, which is an indispensable tool of genius. For only by virtue of imagination can genius ever, according to the requirements of the connection of its painting or poetry or thinking, call up to itself each object or event in a lively image, and thus constantly draw fresh nourishment from the primary source of all knowledge, perception. The man who is endowed with imagination is able, as it were, to call up spirits, who at the right time reveal to him the truths which the naked reality of things exhibits only weakly, rarely, and then for the most part at the wrong time. Therefore the man without imagination is related to him, as the mussel fastened to its rock, which must wait for what chance may bring it, is related to the freely moving or even winged animal. For such a man knows nothing but the actual perception of the senses: till it comes he gnaws at conceptions and abstractions which are yet mere shells and husks, not the kernel of knowledge. He will never achieve anything great, unless it be in calculating and mathematics. The works of plastic and pictorial art and of poetry, as also the achievements of mimicry, may also be regarded as means by which those who have no imagination may make up for this defect as far as possible, and those who are gifted with it may facilitate the use of it.