A central bond, a cherished value, a unique relationship, a profound human need, a type of love. What is the nature of friendship, and what is its significance in our lives? How has friendship changed since the ancient Greeks began to analyze it, and how has modern technology altered its very definition? In this fascinating exploration of friendship through the ages, one of the most thought-provoking philosophers of our time tracks historical ideas of friendship, gathers a diversity of friendship stories from the annals of myth and literature, and provides unexpected insights into our friends, ourselves, and the role of friendships in an ethical life. A. C. Grayling roves the rich traditions of friendship in literature, culture, art and philosophy, bringing into his discussion familiar pairs as well as unfamiliar - Achilles and Patroclus, David and Jonathan, Coleridge and Wordsworth, Huck Finn and Jim. Grayling lays out major philosophical interpretations of friendship, then offers his own take, drawing on personal experiences and an acute awareness of vast cultural shifts that have occurred. With penetrating insight he addresses internet-based friendship, contemporary mixed gender friendships, how friendships may supersede family relationships, one's duty within friendship, the idea of friendship to humanity and ultimately the universal value of friendship.