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 defense 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 Les Pensees ("Thoughts") is a collection of his notes for this incomplete magnum opus.

Because the Pensees were not put in order by Pascal himself, various editors and scholars of his thought have organized these notes in different ways, so it isn't really possible to analyze the work's structure. One can, however, discuss a couple key features.

First, the notes are of varying length and completeness. Some are very short, as short as a single sentence, or seem like only random aphorisms or fragments of larger ideas. Others, however, are long, well thought-out, and/or clearly written in what seems like nearly their final form.

Second, Pascal focuses on both natural religion—knowledge of a Supreme God by reason—and on the Christian faith in particular, through discussion of Scripture. Furthermore, the nature of human beings as not only rational but also volitional and spiritual beings is a major focus. As part of this, one particular argument has become quite famous: the so-called "Wager," which could be summed up in these lines:

Let us weigh the gain and the loss in wagering that God is. Let us estimate these two chances. If you gain, you gain all; if you lose, you lose nothing. Wager, then, without hesitation that He is.

According to Pascal, we are not just thinking machines, but holistic beings, with will, desires, hopes, and fears, and so we must engage with the question of God's existence not just with rational argument but with the question of personal commitment.