From a post written two years ago:
A crucible experience is something which transforms us, and shakes and shapes our lives.
[Many companies go through] through their own crucible moments. They face challenges of various kinds — revenue generation, business model validation, competition, need for additional capital. In fact, some face multiple of these challenges simultaneously. For some, there is a clock ticking away as cash runs out and there is a race to prevent closure. That is always the risk in being an entrepreneur (or investor) and doing things which are different and haven’t been done before. The probability of success is a magnitude lower than what most entrepreneurs believe. For these fledgling companies, this is a moment of truth — a crucible moment. It is a make-or-break period — and one which is easier to describe than to live through.