What does "build on "mean in this sentence? she built on a lifetime of spending time by herself as a reader She built "what" on a lifetime of spending time by herself as a reader? Jacqueline may have been hired for her name and for her social relations, but she soon proved her worth. Her choices, suggestions and widespread social relations were of both to the publishing firms and to Jacqueline herself. In the books she selected for publication, she built on a lifetime of spending time by herself as a reader and left a record of the growth of her mind. Her books are the autobiography she never wrote, Her role as First lady, in the end, was overshadowed by her performance as an editor. However, few knew that she had achieved so much.