More important in its development, however, was the picture. Primitive men all over the world very soon learned to make pictures, very crude and simple to be sure, but indicating fairly well what they stand for. These pictures may be so arranged and conventionalized as to convey a good deal of information. The position of a human figure may indicate hunger, sleep, hostility, friendship, or a considerable number of other things. A representation of a boat with a number of circles representing the sun or moon above it may indicate a certain number of days' travel in a certain direction, and so on indefinitely. This method of writing was highly developed among the North American Indians, who did not, however, get beyond it. [Illustration: Indian picture writing. The biography of a chief.] The next step forward is the attempt to represent abstract ideas by means of pictures. The picture then ceases to represent an object and represents an idea. This is called an ideogram. While it has certain very obvious limitations, it has one advantage over more developed systems. The ideogram does not represent a word; it represents an idea. Consequently it may be intelligible to people who, in spoken language, represent the idea by very different words. For example, there are several cases where a common set of ideograms appears to have been used as a means of communication between people whose spoken language was mutually unintelligible. The Chinese sign for "words" made thus [Illustration: [Chinese character]] is a typical ideogram. It represents a mouth with vapor rising from it. The next step forward is the development of the ideogram into the phonogram, or sound sign. When this step is taken, the ideogram, besides representing an idea in a general way, represents a sound, usually the name of the object represented by the ideogram or by one of its components. A succession of these phonograms then represents a series of sounds, or syllables, and we have a real, though somewhat primitive and cumbrous, written language. Concurrently with this process the original picture has become conventionalized and abbreviated. In this shape it is hardly recognizable as a picture at all and appears to be a mere arbitrary sign. [Illustration: Comparative ideographs.] After a time men discovered that all the sounds of the human voice were really decomposable into a very few and that all human speech, consisting as it does of combinations of these sounds, could be represented by combinations of simple phonograms each of which should represent neither an idea nor a syllable but one of the primary sounds. The phonograms were then greatly reduced in number, simplified in form, and became what we know to-day as letters.