The combinations which can be made with corporeal signs are infinite.  It has been before argued that a high degree of culture might have been attained by man without articulate speech and it is but a further step in the reasoning to conclude that if articulate speech had not been possessed or acquired, necessity would have developed gesture language to a degree far beyond any known exhibition of it.  The continually advancing civilization and continually increasing intercourse of countless ages has perfected oral speech, and as both, civilization and intercourse were possible with signs alone it is to be supposed that they would have advanced in some corresponding manner.  But as sign language has been chiefly used during historic time either as a scaffolding around a more valuable structure to be thrown aside when the latter was completed, or as an occasional substitute, such development was not to be expected.

The process of forming signs to express abstract ideas is only a variant from that of oral speech, in which the words for the most abstract ideas, such as law, virtue, infinitude, and immortality, are shown by Max Mueller to have been derived and deduced, that is, abstracted, from sensuous impressions.  In the use of signs the countenance and manner as well as the tenor decide whether objects themselves are intended, or the forms, positions, qualities, and motions of other objects which are suggested, and signs for moral and intellectual ideas, founded on analogies, are common all over the world as well as among deaf-mutes.  Concepts of the intangible and invisible are only learned through percepts of tangible and visible objects, whether finally expressed to the eye or to the ear, in terms of sight or of sound.

Sign language is so faithful to nature, and so essentially living in its expression, that it is not probable that it will ever die.  It may become disused, but will revert.  Its elements are ever natural and universal, by recurring to which the less natural signs adopted dialectically or for expedition can always, with, some circumlocution, be explained.  This power of interpreting itself is a peculiar advantage, for spoken languages, unless explained by gestures or indications, can only be interpreted by means of some other spoken language.  When highly cultivated, its rapidity on familiar subjects exceeds that of speech and approaches to that of thought itself.  This statement may be startling to those who only notice that a selected spoken word may convey in an instant a meaning for which the motions of even an expert in signs may require a much longer time, but it must be considered that oral speech is now wholly conventional, and that with the similar development of sign language conventional expressions with hands and body could be made more quickly than with the vocal organs, because more organs could be worked at once.  Without such supposed development the habitual communication between deaf-mutes and among Indians using signs is