what is the context of "He poked about with a bit of stick that...

what is the context of "He poked about with a bit of stick that itself was wave-worn and whitened and a vagrant, and tried to control the motions of the scavengers. he made little runnels that the tide filled and tried to crowd then with creatures. He became absorbed beyond mere happiness as he felt himself exercising control over living things. He talked to them, urging them, ordering them. driven back by the tide, his footprints became bays in which they were trapped and gave him the illusion of mastery"?