Used to describe butterfly effect. For want of a nail the kingdom was lost.

the first sight of something / something seen for the first time

one should start a big project with immediate, practical steps; start small / the person who proposes something should be the first one to take practical steps to implement it

let's see; what have we got here

which (of three or more) / which one /

Nothing

what

(archaic) the sky, the heavens / where the smoke collects in an old kitchen using a wood-burning stove / a shelf or shelves above the stove / (archaic) heaven

(archaic) the sky, the heavens / (archaic) heaven / (archaic) the roof of a palace

heavens, sky