If the clothing of the saint was the only light area in the funeral of st. bonaventure, the viewers eye would not be easily drawn to any other areas of the composition.

This sentence is true.
In the composition, we can see people carrying the body of St. Bonaventure to bury him because he died. We can see that he is dressed in white, and if he were the only person painted with light colors, the viewers wouldn't really focus on any other part of the painting. 
I've attached the painting so you can see it.

answer and explanation;

composition refers to both the types of minerals within a rock and the overall chemical makeup of the rock while texture refers to the size and arrangement of the minerals or grains that make up a rock. both composition and texture can be used to classify rocks, such as igneous rocks. texture describes how the rock became solid or crystallized from liquid, melted rock. composition of a rock describes the minerals that make up a particular rock.