the.com/necessity
the mother of invention, and the worst excuse a tyrant ever gave for cruelty.
means Something that is essential or unavoidable — a thing you genuinely must have or do, rather than merely want.
from From Latin necessitas, built on necesse, "unavoidable, inevitable," which itself seems to stitch ne- ("not") to a root tied to cedere ("to give way, yield") — so at its bones a necessity is what does NOT yield, what cannot be stepped around. It reached English in the 14th century through Old French necessite.
roman lawNecessitas non habet legem — necessity knows no law
pitt's lineCalled necessity the plea of every tyrant in 1783
economicsNecessities defy demand curves: people buy them anyway
maslowBasic needs must be met before higher ones surface
philosophySpinoza argued all things happen by absolute necessity