The quote "The heart of a man is like deep water" from Douglas Coupland's novel "Hey Nostradamus!" reflects the complexity and depth of human emotions. It suggests that a person's true feelings and thoughts can be obscured, much like the depths of water which may seem calm on the surface but can hold unseen currents beneath. This metaphor emphasizes that understanding someone’s inner world requires exploration and patience.

In the context of the book, Coupland explores themes of love, loss, and the struggles of human connection. The quote invites readers to recognize that beneath the surface of their interactions lies a rich tapestry of experiences and emotions that are not immediately visible. This deeper understanding can foster empathy and strengthen relationships as individuals learn to navigate the complexities of one another's hearts.