Drive not a second nail till the first is clenched.

Understand the thought

Meaning in plain English

Secure one necessary step before adding another that depends on it. Check the foundation of the next action rather than expanding work on an arrangement that is still unsettled.

What the words are saying

The first nail needs to be secure before attention moves to the second. Figuratively, a person may add commitments or tasks while the arrangement supporting them has not been completed. The image encourages dependable sequencing where one stage really does rely on another. It does not mean that every task must be finished before any separate work can begin; some activities can proceed together without interfering. The practical distinction identifies the actual dependency. A brief check of what is settled and what remains uncertain can prevent an expanding plan from making its unfinished foundation harder to address.

Everyday example

A team confirms who is responsible for maintaining a shared record before adding several new groups whose information will depend on that arrangement.

When to use it

Use it when the next commitment relies on an earlier step that is not yet secure.

Agent-assisted editorial interpretation. This explains the words; it does not by itself verify their author or earliest origin.