What story/example does hill use to demonstrate the power of specialized knowledge?

In his book "Think and Grow Rich", Napoleon Hill does not provide a specific story or example to demonstrate the power of specialized knowledge. Instead, he asserts the importance of it in general terms. He emphasizes that general knowledge is not enough to become wealthy. One must focus on acquiring and applying specialized knowledge in a specific niche. This could be through further education, experience, or by surrounding oneself with knowledgeable individuals. The key is not just gaining the knowledge, but also applying it effectively for success.