Buddhism's entire philosophy fits into four sentences

The Buddha's first sermon after his enlightenment distilled his teaching into four claims: life involves suffering, suffering has a cause (craving), that cause can end, and there's a path to end it. Nearly every later school of Buddhist thought treats these Four Noble Truths as the foundation everything else builds on.

— attributed to the Buddha, Dhammacakkappavattana Sutta — Pali Canon, Samyutta Nikaya