What is the author's style in Gift from the Sea by Anne Morrow Lindbergh?

Gift from the Sea reads like a letter to a long lost friend. The familiar tone assists greatly in getting certain points across, as if the author is giving personalized advice rather than a broad overview of an individual's life. Although the book was published in 1955, most of what the author says still holds true, and through the use of quotations from writers and philosophers throughout the ages, she proves that what may seem to be current issues are in fact universal and ageless.