Pensées

Blaise Pascal is both a philosopher, a religious thinker and a mathematician. Pascal is considered the forerunner of existentialist philosophy, developed later by Kierkegaard, Heidegger and Sartre.
Before his death in 1662, the French mathematician Blaise Pascal, who was also a dedicated Christian, had planned to write a philosophical and theological work that would be both a rational defence of the Christian faith and perhaps a spiritual autobiography, along the lines of Augustine's "Confessions". He did not survive to complete this work, however, and the work known as the "Pensées" ("Thoughts") is a collection of his notes for this incomplete magnum opus.

Because the "Pensées" were not put in order by Pascal himself, various editors and scholars of his thought have organised these notes in different ways, so it isn't really possible to analyse the work's structure. 

"Pensées" is considered to be his major work and was published a short time after his death in 1662 and address a number of different points, one of the chief being the fallibility of humans and vastness of God's love for mankind.