The interaction between any two issues - A and B, represented by the two boxes - can be illustrated by their relative proximity. The two issues are of equal importance, but their proximity determines how closely they are associated with each other.

Look at the three cases above - in Case 1, the two boxes are touching each other, meaning the issues are very proximate and closely linked to each other. In Case 3, they are relatively far apart - meaning the relationship between them is weak.