Answer:
This is a quote by Jack London, from the third chapter (The Dominant Primordial Beast) of his book "The call of the wild." The quote is used to describe when the team spots a rabbit one night, fifty dogs from the Northwest Police camp go on to hunt it, with Buck leading the pack.
Step-by-step explanation:
The ecstasy that describes, refers to the moment when one feels most alive, which, ironically, makes us forget about being alive, as we just find ourselves at the moment, unaware of anything else. London describes this feeling as what an artist might feel while making a passionate work of art, or what a soldier feels in the heat of battle. And definitely, what Buck felt at that moment, leading the pack in a race influenced by a primal instinct he thought forgotten.