Sentence:  Emerson - <WSD>Platonist</WSD> , idealist , doctrinaire - sounded a high Transcendental note in his `` Boston Hymn '' , delivered in 1863 in the Boston Music Hall amidst thundering applause : `` Pay ransom to the owner and fill the bag to the brim . 
Meaning of the word marked with <WSD> tags:  an advocate of Platonism