Maslow used the terms "physiological", "safety", "belonging and love", "social needs" or "esteem", and "self-actualization" to describe the pattern through which human motivations generally move. This means that in order for motivation to occur at the next level, each level must be satisfied within the individual themselves.
copy from wiki
用金字塔嘅原因都係因為咁
冇咗低層就起唔到上層