nature

call of nature used euphemistically to refer to a need to urinate or defecate.

get (or go) back to nature return to the type of life (regarded as being more in tune with nature) that existed before the development of complex industrial societies.

in the nature of things inevitable or inevitably.

2002Economist The IMF sometimes makes mistakes. It is in the nature of things: the Fund practises battlefield medicine.

in a state of nature

1 in an uncivilized or uncultivated state.

2 totally naked.

3 (in Christian theology) in a morally unregenerate condition, unredeemed by divine grace.

nature red in tooth and claw: seered.

the nature of the beast the inherent or essential quality or character of something, which cannot be changed and must be accepted. informal

second nature: seesecond.

your better nature the good side of your character; your capacity for tolerance, generosity, or sympathy.

2013Eric S. RaymondArmed & Dangerous Never appeal to a man's 'better nature'. He may not have one. Invoking his self-interest gives you more leverage.