No animal has captured the human imagination quite like the horse, depicted in cave drawings thousands of years ago through countless renderings in paint, clay, ink, even film. In his first book, award-winning photographer Tim Flach's quest to document the horse has resulted in ''Equus'', an intensely moving look at an animal - as solitary subject and en masse, from the air and from underwater - whose history is so powerfully linked to our own. From exquisite Arabians in the Royal Yards of the United Arab Emirates to purebred Icelandic horses in their glacial habitat; from the soulful gaze of a single horse's lash-lined eye to the thundering majesty of thousands of Mustangs racing across the plains of Utah, ''Equus'' provides an amazing and unique insight into the physical dynamics and spirit of the horse.