Rebuilding Rails: What Does a Rails Expert Know About Debugging That You Don't? (rebuilding-rails.com)

Brilliant idea. In order to learn more about Ruby on Rails, the course takes you on a journey in which you build Ruby on Rails from scratch.

This could go a long way towards removing the magic and actually understanding how Rails works, and why it is designed that way.

This was written by the recently deceased Noah Gibbs. The site is now under the control of his widow. It's a great course and I'd encourage people to check it out.