In the expert from H. H Munro’s “The Open Window”, which line is an example of direct characterization?

[he] let his gaze wander to the swirling water of the stream racing madly beneath his feet. a piece of dancing driftwood caught his attention and his eyes followed it down the current. how slowly it appeared to move! what a sluggish stream! what contrasting words are used to describe the stream in this passage?