The hypothesis that the construction of thought appears through a pre-verbal form of writing led Freud to replace the usual analogy between ontogenesis – the development of the individual – and phylogenesis – the development of the species to which the individual belongs – with an analogy between the genesis of thinking in the individual and the genesis of writing in the species:11
Let us recall that we have said that the dream-work makes a translation of the dream-thoughts into a primitive mode of expression similar to picture-writing. All such primitive systems of expression, however, are characterized by indefiniteness and ambiguity of this sort (…) The coalescence of contraries in the dream-work is, as you know, analogous to the so-called ‘antithetical meaning of primal words’ in the most ancient languages (…)
The old systems of expression – for instance, the scripts of the most ancient languages – betray vagueness in a variety of ways which we would not tolerate in our writing to-day. Thus in some Semitic scripts only the consonants in the words are indicated. The reader has to insert the omitted vowels according to his knowledge and the context. The hieroglyphic script behaves very similarly, though not precisely in the same way; and for that reason the pronunciation of Ancient Egyptian remains unknown to us. The sacred script of the Egyptians is indefinite in yet other ways. For instance, it is left to the arbitrary decision of the scribe whether he arranges the pictures from right to left or from left to right. In order to be able to read it one must obey the rule of reading towards the faces of the figures, birds, and so on. But the scribe might also arrange the pictographs in vertical columns, and in making inscriptions on comparatively small objects he allowed considerations of decorativeness and space to influence him in altering the sequence of the signs in yet other ways. The most disturbing thing about the hieroglyphic script is, no doubt, that it makes no separation between words. The pictures are placed across the page at equal distances apart; and in general it is impossible to tell whether a sign is still part of the preceding word or forms the beginning of a new word.
(Freud, 1916–1917 [1915–1917], pp. 229–230)