The English term “happiness” is a translation of the Latin felicitas (AT X 361, CSM I 10; AT VII 52, CSM II 36) and its French equivalent félicité, as found in Descartes’ writings, especially in the correspondence with Princess Elisabeth. This notion is the same as “blessedness,” which appears frequently beginning with Descartes’ comments on Seneca's De vita beata (AT IV 263, CSMK 256–57). Happiness in the sense of félicité is distinct from the fortuitous occurrence of being happy (bonheur) insofar as the former depends not on chance or good fortune but rather on us alone (AT IV 264, CSMK 257).

The notion of félicité is linked to that of satisfaction (contentement) since Descartes defines it as the perfect satisfaction of mind resulting from the possession of the “sovereign good for us” (AT IV 264, 275, 277, 305, CSMK 257, 261, 261–62, 268; AT V 81–86, CSMK 324–26). Although far more rarely, Descartes also uses the notion of voluptuousness or pleasure in order to indicate what this deeper happiness (or “beatitude”) consists in (AT X 361, CSM I 10; AT VII 52, CSM II 36; AT IV 276–77, CSMK 261).

Finally, Descartes’ reflections on happiness remain within the framework, inherited from Scholasticism, of the distinction between natural and supernatural beatitude (AT VII 52, CSM II, 36; AT IV 267, 285, 314, CSMK 258, 264, 272; AT V 82, CSMK 324). While Descartes concentrates exclusively on the happiness naturally available to man, he recognizes that there is another and higher happiness that does not fall within the domain of philosophical thought.