 At this point , for a period which coincided with the birth and childhood of his natural son , <unk> @-@ Miriam Delaborde ( 1839 – 1913 ) , Alkan withdrew into private study and composition for six years , returning to the concert platform only in 1844 . Alkan neither asserted or denied his paternity of Delaborde , which , however , his contemporaries seemed to assume . Marmontel wrote <unk> in a biography of Delaborde that " [ his ] birth is a page from a novel in the life of a great artist " . Alkan gave early piano lessons to Delaborde , who was to follow his natural father as a keyboard virtuoso . 
