Sentence:  In contrast to this Stoic patristic view , Utopia implies that the nature of man is such that to rely on individual conscience to supply the deficiencies of municipal law is to embark on the bottomless sea of human sinfulness in a <WSD>sieve</WSD> . 
Meaning of the word marked with <WSD> tags:  a strainer for separating lumps from powdered material or grading particles