Sentence:  The concern of Utopia <WSD>is</WSD> with the optimo reipublicae statu , the best ordering of a civil society ; and it is again and again made clear that Utopian communism provides the institutional array indispensable to that best ordering . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)