Pascal, his belief and religious commitment revitalized, in January 1655 visits the older of two convents at Port-Royal for a two-week retreat.

He will regularly travel for the next four years between Port-Royal and Paris.

It is at this point, immediately after his conversion, that he begins writing his first major literary work on religion, the Provincial Letters, set in the conflict between Jansenists and Jesuits.

In this year, he also writes an important treatise on the arithmetic of triangles.