Here's what it represents:
* The value of effort and perseverance: Mr. Murry uses this phrase to encourage Meg and her brother Charles Wallace to keep trying even when faced with difficult challenges. He implies that real progress comes through hard work and dedication, not just talent or intelligence. The "work" refers to the effort and determination required to achieve a goal, and the "craftsman" is the individual who skillfully applies that effort.
* The process of learning and growth: The line also suggests that achieving something worthwhile is a journey, not a destination. It's about the continuous process of learning and improvement, refining skills and knowledge through experience.
* The importance of trusting the process: Mr. Murry, a theoretical physicist, understands that scientific breakthroughs often require years of research and experimentation. He uses this phrase to remind Meg and Charles Wallace that they shouldn't be discouraged by setbacks or failures. The journey itself is a form of craftsmanship, even if the final outcome is uncertain.
In essence, "work proves craftsman" is a reminder that success isn't solely determined by talent or luck. It's a testament to the power of dedication, perseverance, and the continuous process of learning and growth.