I think in this quote, Zeus is referring to the fire as the "evil thing in which they may take pleasure to their gut," because he refers to it right before he uses the word evil to describe it.
This is one GREAT drawing tip that I always tend to use.
To shade:- To make it look like the person has contour, you can shade it with the pencil, then, smudge the place shaded with your finger...(rub on it). We do this so that it could look like a shaded area, it will make it look fabulous!
Try to make it look different:- Don't copy anything anyone makes, try to make it unique by adding shades, cold and warm.
C) The composer may wish to use certain instruments to support other instruments; as the bass and harmony support the melody.