Prayer is derived from Pray. Pray is related to Spiritual. Spiritual is a synonym of Potential. 
you are likely to find Dust in/at/on Library. you are likely to find Reader in/at/on Library. Reader is the opposite of Author. 
Prayer --DerivedFrom--> Pray <--RelatedTo--> Spiritual <--Synonym--> Potential 
Dust --AtLocation--> Library <--AtLocation-- Reader <--Antonym--> Author 