"The poet's eye in a fine frenzy rolling, Glances from heaven to earth, from earth to heaven; And as imagination bodies forth The forms of things unknown, the poet's pen Turns them to shapes, and gives to airy nothing A local habitation and a name." These lines suggest that the first step in invention is made almost without effort; that a picture, confused and dim but actual, is made by the imagination on the mental retina; and that, after that, the constructive faculties arrange the elements of the picture in such wise as to produce a clear and definite entity. Regarded in this way, the inventor of mechanical appliances suddenly sees a confused and dim picture of an instrument or a mechanism (or a part of it) that he has never seen with his bodily eyes; the musical composer hears imperfectly and vaguely a new musical composition; the sculptor sees a statue, the painter sees a new combination of objects and colors producing a new effect, and the poet feels the stirring in him of vague, but beautiful, or powerful or inspiring thoughts. If now the picture is allowed to fade, or if the constructive faculty is not able to make it into an actuality, or if the picture has not in itself the elements which the state of civilization then prevailing make it possible to embody in an entity, no invention of a mechanical appliance is made, no plan of campaign, no musical composition, no statue, no painting, no poem is produced. If, however, the constructive effort develops successfully the conception that the imagination made, and if the circumstances of time and place are all propitious, then the art of making fire at will is born, or Bonaparte's suggestion at Toulon is made, or the strains of Beethoven's music inspire the world, or the statue of Moses is carved, or the Immaculate Conception is pointed, or Hamlet is written, or the electric telegraph binds the peoples of the earth together.