This chestnut comes from my father. He would often use it to stop us kids from making excuses for failures, and to encourage us to take responsibility. People who spout this cliche often want to deflect blame away from their direction. Unfortunately, it overshoots the mark and can be damaging to people who have a tendency towards self blame.

The problem with the quote is that failure is often caused by a myriad of factors, rather than just one constant fault. To continue the trade analogy, the weather may have been unsuitable, or the materials defective. The tools may in fact have been inadequate.

Taking personal responsibility for failure is not always appropriate and can mask the real cause of failure. The truth in the proverb comes from the tendency for the 'poor workman' to continuously blame one thing - be it his tools or whatever - without taking time to find out the real cause. A workman who continuously blames himself is also a poor workman, and one who will have a very short career before the weight of all the blame causes him to quit.

A good workman will not be afraid of blaming his tools. A good workman will find where the blame really lies rather than placing default blame on himself. A superlative workman will have no fear of exposing the fault.