It certainly may be made a power in the human soul; but it is a power which has feeling, not knowledge, for its base. It may be, and will be, and we hope is turned to account, both in steadying and strengthening the intellect, and in rescuing man from that littleness to which, in the struggle for existence, or for precedence in the world, he is continually prone. EARLIER THOUGHTS.[8] A WORK recently published by Mr. Murray contains a sketch of the grounds on which the most advanced scientific thinkers of the present day base their convictions as to the physical character of Light and Heat. The fundamental idea there developed is, that the phenomena of light and heat, like those of sound, are essentially _mechanical_. Precisely the same reasoning applies to the vibrating ether which produces the one as to the vibrating air which produces the other, and both are dealt with substantially as we should deal with the waves of a liquid or the swing of a pendulum. Reflection on this subject has suggested the thought that the considerations brought forward in the sketch referred to may apply themselves to certain phenomena which are usually considered to lie outside the pale of physics, and thus may indicate new relationships between man regarded as a being of intellect and emotion, and the wondrous material system in the midst of which he dwells. All our intercourse with the external world consists exclusively in an interchange of motion. From a vibrating, sonorous body, for example, pulses are sent to the ear and stir the auditory nerve to motion. From a luminous body pulses are sent to the eye, and stir the optic nerve to motion. Other pulses of different periods strike upon other nerves, and produce the sensation of heat; but, in all cases, whether it be light, or sound, or ordinary feeling, the excitement of the nerves, regarded more strictly, is the excitement of motion. And if the motion be induced by internal causes instead of external, is it not fair to infer that the effect on consciousness will be the same? Let any nerve, for example, be thrown by morbid action into the precise state of motion which would be communicated to it by the pulses of a heated body, surely that nerve will declare itself hot--the mind will accept the subjective intimation exactly as if it were objective. The retina, as is well known, may be excited by purely mechanical means. A blow on the eye will cause a luminous flash, and the mere pressure of the finger on the external ball will produce a star of light, which Newton compared to the circles on a peacock’s tail. Disease makes people see visions and dream dreams; but, in all such cases, could we examine the organs implicated, we should, on philosophical grounds, expect to find them in that precise molecular condition which the real objects, if present, would superinduce.