The central theme of the quote "Does a man complete only with love?" from Naguib Mahfouz's book "Palace Walk" explores the complexities of human relationships and the essence of fulfillment in life. The quote suggests that love alone may not be enough for a man to feel whole. It raises questions about the significance of other aspects of life, such as duty, ambition, and personal identity, which also contribute to a person's sense of completeness.