In most of the unsuccessful attempts at interpreting the Indus script, the "method" has consisted of comparing other pictographic scripts and supposing that the Indus signs have been pronounced like the similar- looking foreign signs. However, as a rule, different pictographic scripts have been used to write different languages, and their similar-looking signs have denoted words that have little in common in pronunciation (Fig. 3).
But if one abstains from unlikely conclusions regarding the phonetic value of Indus signs, comparisons of this kind are by no means useless. Irrespective of whether there is any genetic connection or not, similar- looking signs of other pictographic scripts provide valuable clues to the pictorial meaning of the Indus signs (Fig. 3).
3. The Indus script and other early writing systems.
In this respect still more important hints are given by the archaeological remains of the Indus civilization and its antecedent neolithic cultures, including such things as architecture, tools and weapons, and art. Artistic expression on painted pottery (Fig. 4) and in the iconographic motifs of the seals and amulets are of particular significance, since they let us see directly how the Indus people represented various objects.
Why all this concern about finding the pictorial meaning of the Indus pictograms?
Because their pictorial shapes constitute one of the chief keys to their interpretation. If a pictogram has been used in its primary, pictorial meaning, its meaning can be understood directly from the iconic 2 sign itself, irrespective of how the corresponding word was pronounced in the language underlying the Indus script.
4. Pots from Mundigak IV
Unfortunately, the pictorial meaning of most Indus signs is difficult to recognize. As in many other scripts, the demand for fluency in writing has led to a radical simplification of their shape. The characteristic elements have been reduced to the barest essential. Fortunately this tendency has not gone as far as in the Sumerian script, where the pictorial shapes of the earliest phase soon gave way to abstract cuneiform symbols: if we did not have an unbroken chain of successive forms, it would be impossible to reconstruct their pictorial prototypes.
But however important insights into the contents of the documents they might give, purely pictorial interpretations are hard to check and cannot alone constitute a decipherment of the script. By definition, this term implies a plausible identification not only of how the script functions but also of the underlying language, together with actual sign interpretations that are sufficiently cross-checked to carry conviction.
[Originally published as Parpola, Asko (1988) Religion reflected in the iconic signs of the Indus script: penetrating into long-forgotten picto+graphic messages. Visible Religion 6: pp. 114-135.]