"When, in the first stage of writing, a sign stood for a word, there were required, of course, as many symbols as there were words in the language. When the signs were employed to represent syllables, a great advance over the use of word signs had been made, but the method was still a clumsy device by which to express ideas. It was only when symbols finally represented the elementary sounds of the human voice that they became true letters. When writing was entirely pictorial, in the effort to secure greater rapidity of execution simpler forms were developed, and finally, letters. The sense, in a similar manner, declined from the idea suggested by the picture into a mere syllable without concrete meaning, and finally to simple sounds corresponding to letters. The various steps from pictures to words seem to have been taken in prehistoric times by different peoples independently. To which people must we trace our own alphabet?"
The Alphabet and Elements of Lettering; Frederic W. Goudy (1918)