Nut

A hard nut to crack. A difficult question to answer; a hard problem to solve. (Anglo-Saxon, hnut, a nut.)

He who would eat the nut must first crack the shell. The gods give nothing to man without great labour, or “Nil sine magno vita labõre dedit mortalibus.” “Qui nucleum esse vult, frangit nucem” (Plautus). In French, “Il faut casser le noyau pour en avoir lʹamande.” It was Heraclīdes who said, “Expect nothing without toil.”

If you would reap, you also must plough;