Some commentators suppose a reference is here made to names written on earth in opposition to names written in heaven; others think the reference is to words written in the dust in contrast to words engraved in the rock. As the former are easily obliterated and forgotten, so will be the fate of those who depart from the Lord.
We have no direct evidence that writing in the dust was actually practiced in the days of Jeremiah. The figure used in the text might readily suggest itself aside from any custom. It may not be inappropriate, however, to observe that this mode of writing has been practiced in some schools in the East. Harmer says that Peter della Vallé noticed a simple way of “writing short-lived memorandums in India, where he beheld children writing their lessons with their fingers on the ground, the pavement being for that purpose strewed all over with very fine sand. When the pavement was full they put the writings out; and, if need were, strewed new sand from a little heap they had before them wherewith to write farther” (Observations, vol. 3, p. 128, note).