What does Proverbs 27:1 mean?

No human being can infallibly predict what will happen in the future. Some predictions are reasonably secure, such as that the sun will rise. Others are dependent on circumstances, and some can be wildly unpredictable. A wise person makes plans (Proverbs 16:3; 20:18; 24:27) but takes his fallibility into account. Making well-reasoned choices is different from arrogantly ignoring risks.

The word "boast" translates a Hebrew root word rendered as "praise" later in this passage (Proverbs 27:2). No one should praise himself for what he hasn't yet accomplished. A common English statement warns "don't count your chickens before they're hatched," meaning not all eggs necessarily become birds. Things our human minds expect to happen might not happen, so we shouldn't speak of them as absolute guarantees. Such is the attitude criticized by the apostle James (James 4:13–16). He explains, "You do not know what tomorrow will bring" (James 4:14). The same verse notes that life is not only uncertain, but it is also brief. Rather than overconfidence, we should approach the future with a sense of humility. "If the Lord wills, we will live and do this or that" is a better attitude (James 4:15).