"The portraits, of more historical than artistic interest, ha..." — W.B. Yeats quote meaning

The portraits, of more historical than artistic interest, had gone; and tapestry, full of the blue and bronze of peacocks, fell over the doors, and shut out all history and activity untouched with beauty and peace; and now when I looked at my Crevelli and pondered on the rose in the hand of the Virgin, wherein the form was so delicate and precise that it seemed more like a thought than a flower, or at the grey dawn and rapturous faces of my Francesca, I knew all a Christian's ecstasy without his slavery to rule and custom; when I pondered over the antique bronze gods and goddesses, which I had mortgaged my house to buy, I had all a pagan's delight in various beauty and without his terror at sleepless destiny and his labour with many sacrifices; and I had only to go to my bookshelf, where every book was bound in leather, stamped with intricate ornament, and of a carefully chosen colour: Shakespeare in the orange of the glory of the world, Dante in the dull red of his anger, Milton in the blue grey of his formal calm; and I could experience what I would of human passions without their bitterness and without satiety. I had gathered about me all gods because I believed in none, and experienced every pleasure because I gave myself to none, but held myself apart, individual, indissoluble, a mirror of polished steel: I looked in the triumph of this imagination at the birds of Hera, glowing in the firelight as though they were wrought of jewels; and to my mind, for which symbolism was a necessity, they seemed the doorkeepers of my world, shutting out all that was not of as affluent a beauty as their own; and for a moment I thought as I had thought in so many other moments, that it was possible to rob life of every bitterness except the bitterness of death; and then a thought which had followed this thought, time after time, filled me with a passionate sorrow.