Final answer:
The passage 'All in the Day's Work' by Ida M. Tarbell emphasizes the idea that women can achieve independence through will and purpose, highlighting the shift from traditional domestic roles to education and professional involvement.
Step-by-step explanation:
The central idea of the passage 'All in the Day's Work' by Ida M. Tarbell is that independence can be gained through a sense of will and purpose. This is evidenced by the discussion on how women used their education to assert their independence in an era where their roles were expected to be predominantly domestic. The passage points out the struggles against societal norms that women faced, and how they overcame them by demonstrating their capability in both educational and professional spheres.