Sir Rabindranath Tagore, the noted Indian poet, musician, educator and winner of the Nobel Prize in literature in 1913, will speak at Tremont Temple, Boston, tonight. The subject of his lecture will be "The Cult of Nationalism." Tagore has been acclaimed by many as the greatest living poet. His writings reflect the romantic spirit of the East, and most of his poems are written to a weird moaning Rengali music, which he himself composes. He has translated many of his own works, among them his short stories in the writing of which many critics claint his greatest genius lies. Tickets ranging in price from 50 cents to $1.52 may be purchased at the box office.