Answer:
When Zinsser compares writing to the craft of carpentry, he is emphasizing the importance of attention to detail and the value of hard work and practice in both endeavors.
Like a carpenter, a writer must be skilled in the use of tools, in this case, the tools of grammar, vocabulary, and syntax. A carpenter must choose the right materials, measure twice, and cut once. Similarly, a writer must choose the right words, construct sentences that flow logically, and make sure that their meaning is clear.
Zinsser also emphasizes that both carpentry and writing require practice and discipline. A carpenter must put in hours of work to master their craft, and a writer must write regularly and be willing to revise and refine their work until it is polished and effective.
Finally, Zinsser notes that both carpentry and writing can be rewarding in their own right. A carpenter can take pride in creating something tangible and useful, while a writer can take pride in crafting a beautifully written passage or in communicating an important idea to their audience.
Overall, Zinsser's comparison of writing to carpentry highlights the importance of attention to detail, hard work, and practice in both endeavors, and emphasizes that both can be rewarding and fulfilling pursuits for those who are willing to put in the time and effort required to master their craft.