A single 1943 paper claimed all human motivation fits into five stacked needs

Abraham Maslow proposed that people pursue needs in a rough order: physiological survival, safety, belonging, esteem, and finally self-actualisation, the drive to fulfil your own potential. He never drew the now-famous pyramid himself; management consultants added that decades later. The theory remains hugely influential despite critics noting the order isn't strictly fixed and the higher needs are hard to test.

— Abraham Maslow, A Theory of Human Motivation — Psychological Review, 1943