Speech can, by means of reflex memory, produce at will the particular images already classified in the mind, and this makes the process of reasoning possible; since such a process becomes more easy by the use of signs to which the attention can revert.  The relative size of objects, and the like qualities, which are at first regarded as so many different intuitions in space, are defined by words or gestures, and are thus subjected to comparative analogy; but in the early stages of language these relations were presented in an extrinsic form by phonetic signs, and became images which in some sort represented one particular state of consciousness with respect to the two things compared.  Galton, speaking of the Damaras, tells us that they find great difficulty in counting more than five, since they have not another hand with which to grasp the fingers which represent the units.  When they lose any of their cattle, they do not discover the loss by the diminution of the number, but by missing a familiar object.  If two packets of tobacco are given to them as the regulation price of a sheep, they will be altogether at a loss to understand the receipt of four packets in exchange for two sheep.  Such examples might be multiplied to any extent.

We repeat that when not endowed with speech, or some analogous means, animals and man think in images, and the relations between these images are observed in the simultaneousness and succession of their real differences; these images are combined, associated, and compared by the development of reflex power, and hence arises the estimate of their concrete relations.  Of this we have another proof, observed by Romanes in a lecture on the intelligence of animals, and confirmed by myself, in the condition of deaf-mutes before they are educated, in whose case the extrinsic sign and figure takes the place of the phonetic and articulate sign.  Where speech is wanting, it is still possible to follow a conscious and imaginative process of reasoning, but not to rise to the higher abstract ideas which may be generated by such reasoning.  The thought of deaf-mutes always assumes the most concrete form, and one who was educated late in life informed Romanes that he had always before thought in images.  I know no instance of a deaf-mute who has independently attained to an advanced intellectual stage, or who has been able without education to form any conception of a supernatural world.  R.S.  Smith asserts that one of his deaf-mute pupils believed, before his education, that the Bible had been printed in the heavens by a printing press of enormous power; and Graham Bell speaks of a deaf-mute who supposed that people went to church to do honour to the clergyman.  In short, the intellectual condition of uneducated deaf-mutes is on a level with that of animals, as far as the possibility of forming abstract ideas is concerned, and they think in images.  There is a well-known instance in the deplorable condition of Laura Bridgman, who from the time she was two years