The quote from Diana Gabaldon's "Written in My Own Heart's Blood" compares the fields of plumbing and medicine, emphasizing the practical knowledge professionals gain early in their training. Both professions demand a hands-on approach where certain skills—and boundaries—must be respected. In plumbing, sticking one's fingers in the mouth would be unwise, just as in medicine, where one must adhere to strict hygiene and protocols to ensure safety and health.

This analogy highlights the critical importance of training and experience in both trades. It suggests that just as a plumber learns about the risks of contamination, a doctor becomes acutely aware of the need for cleanliness and care to avoid spreading infections or diseases. Ultimately, each profession carries its own set of rules that are vital for success and safety.