From the early days of search engine optimization, keywords and content have always been vital to achieving your goals. Starting back in the days when we used to shove every slightly relevant keyword into our Meta tags, it has been obvious that search engines love text. The more advanced the engines have gotten over the years, the more complex and sophisticated many writers have gotten with their search engine copywriting.
Supposed formulas, saturation levels, and other mysterious concoctions have been developed to help us outsmart the engines. However, what we should have been doing all along was writing for the visitor first and the engines second. Why? Because creating a site that's loved by visitors is a prime factor in linking, ranking, and marketing as a whole. As the engines make great strides with more personalized and efficient searches (such as semantic search) natural search engine optimization writing is even more important.