If French was the ‘vulgar tongue’ at the time, then a translation from this mother tongue into Latin can be said to amount to a conversion into the paternal language, the language of institutions and dominant norms.
Descartes also deliberately did not address certain issues in the Discours. He did not, for example, debate the arguments of the skeptics who doubted the existence of God. Being in the ‘vulgar tongue’, those issues would ‘disturb weaker minds’, as he put in a letter of May 1637. Interestingly, in a letter of February 1638 he makes the same point, only now he speaks of his book ‘which I wished to be intelligible even to women’.