Light To illuminate Obscurity To obscure Shadow To overshadow Morning To darken Day To clear away Twilight To blind Gloom To cloud --those actions, processes, or operations which take place or are produced in the outer world, physical or material, and in the inner world, intellectual or moral. Were your pretended "image" the result of purely personal impressions,--all persons are not equally apt in apprehending those fictitious relations which are the food of poetry,--were it, in a word, no more than an individual conception, and, therefore, eminently variable, I should not hesitate to accept your opinion: we should simply be discussing what are called, in scholastic language, the individual sense (_sens propre_) and the imaginative sense (_sens figuré_). But there exists upon this point an unanimous and universal agreement: all languages, living or dead, attest it; it embraces the aggregate of the members of the human family. * * * * * This is the _first_ point which induces me to doubt the legitimacy of the proposed explanation. But I am confirmed in my hesitation by numerous other facts. Let us emerge from the domain of rhetoric to enter that of experimental physiology and psychology. Too powerful a light blinds the organs of seeing. No mortal eye, unless with the aid of artificial appliances, can gaze upon the sun, the great source of light. If the vision is to act clearly, we must proceed step by step. If from a very light apartment we pass rapidly, and without transition, into a darkened room, or _vice versâ_, we feel temporarily blinded: the eye demands a short time to recover, as it were, from its astonishment. If we fix our gaze for one or two minutes on a star of the first magnitude, as, for example, Sirius, and afterwards turn away abruptly, the eye will for a while remain insensible to stars of a less intense splendour. These are incontestable physiological facts, which anybody may easily verify for himself. * * * * * Well, in the psychological order facts exist which are in all respects analogous. Take one of those truths which the human thought, labouring generation after generation, has taken centuries to discover or elucidate; place it suddenly before an unprepared mind; however luminous may be this truth, it will be simply shadow and darkness to the mind we speak of; it will not comprehend an iota of it. Why? For the very obvious reason that it lies outside its sphere of ideas, in every respect comparable to the sphere of vision, beyond which and within which there is no more room for the sensorial impressions. There, as here, we must proceed gradually, and arrange the transitions so as to produce the desired results. * * * * *