Common Sense on Mutual Funds John C. Bogle (Author)

The main message is that costs  matter,  simplicity is the best way to avoid costs. Investment Strategy covering Long-Term Investing, Nature of Returns, Asset Allocation and Simplicity is Part 1 of the Book.

Buy low cost broad-based index funds.  These funds are highly likely to outperform the vast majority of actively managed portfolios and mutual funds in the long run.  Low cost broad-based index fund achieves the average market returns minus low fees and minimum taxes.  The index investor will thus outperform the average investor in actively managed mutual funds given all the extra costs and taxes associated with active management.  Also notice the reduced compounding of costs over the years will lead to an even greater index fund performance in the long run.