'Tis hard to sail o'er the sea in an egg-shell.

A vast or demanding undertaking becomes perilous when the means available are too frail for the task. The egg-shell suggests a vessel that cannot reliably protect its traveler.

The proverb warns against relying on resources that are strikingly unequal to the challenge. It emphasizes the difficulty and risk of the attempt rather than declaring success impossible.

Use it to question a plan that asks a fragile tool, small budget, or inadequate preparation to bear a much larger burden. Its image suits a pointed warning about the mismatch between an undertaking and the means proposed for it.