Very occasionally you read a book that you sense has altered your DNA and for me this was Peter Matthiessen&rsquos The Snow Leopard. It&rsquos a tale about Matthiessen&rsquos expedition &mdash shortly after his wife died from cancer &mdash with a naturalist friend to the remote, mountainous region of Dolpo in northwest Nepal near the border of Tibet. One of the aims of their trip is to record the activities and habitat of the endangered snow leopard. This is high-octane adventure threaded with wonderful natural history description &mdash which alone would have made for marvellous reading. But what emerges is something far more courageous and profound an exploration into the nature of things &mdash transience, presence and absence, friendship, memory, acceptance and longing. It&rsquos almost impossible to write convincingly about the intangible, or to express genuine intimations of mystery and otherness, but Matthiessen does this with such a light touch and in such uplifting prose that you feel like you&rsquore soaring above those very mountain peaks that persistently, ominously, shadow their journey. Though he comes close, he never sees a snow leopard. And this, in a way, is the key of this hauntingly beautiful book.

Isabella Tree is a travel writer and biographer whose latest book is The Living Goddess