The sea rippled against the mountain, and reeds, the emblems of humility, ever yielding to the wave that swept them, clustered round the shore. Dante and Virgil went down to the margin, and there the living poet bathed away the stains and tears of Hell. Ere long the waves were skimmed by a light bark, a radiant angel standing in the prow, bearing the souls of the redeemed, who must yet be purified, singing the psalm, 'When Israel came out of Egypt.' Amongst the shades thus borne to the mount of purification was Dante's friend Casella, the singer and musician. How often had his voice lulled all Dante's cares to sleep, and 'quieted all his desires,' and now it seemed as though he were come to bring his troubled heart to peace, to rest him in his utter weariness of body and of soul. So, at his entreaty, Casella raised his voice, and all the shades gathered entranced around him as he sang a noble canzone composed by Dante himself in years gone by.[59] The sweet sound never ceased to echo in the poet's memory--not even the ineffable harmonies of Paradise drowned those first strains of peace that soothed him after his awful toil. But Purgatory is no place of rest, and Casella's song was rudely interrupted by the guardian of the place, who cried aloud, 'How now, ye sluggard souls! What negligence and what delay is here? Speed to the mountain! Rid you of the crust that lets not God be manifest to you!' To purge away our sins is not to rest; and no longing for repose must tempt us to delay even for a moment.[60] Dante draws no flattering picture of the ease of self-purification; Hell itself hardly gives us such a sense of utter weariness as the first ascent of the mount of Purgatory. Virgil is on in front, and Dante cries out, altogether spent, 'Oh, my sweet father, turn thou and behold how I am left alone unless thou stay;' but Virgil still urges him on, and after a time comforts him with the assurance that though the mountain is so hard to scale at first, yet the higher a man climbs the easier the ascent becomes, till at last it is so sweet and easy to him that he rises without effort as a boat drops down the stream: then he may know that the end of his long journey has come, that the weight of sin is cast off, that his soul obeys its own pure nature, and rises unencumbered to its God.[61]