Mary, who having, in consequence of being the only plain one in the family, worked hard for knowledge and accomplishments, and was always impatient for display... had neither genius nor taste, and though vanity had given her application, it had given her likewise a pedantic air and conceited manner, which would have injured a higher degree of excellence than she had reached. Elizabeth, easy and unaffected, had been listened to with much more pleasure, though not playing half so well; and Mary,at the end of a long concerto, was glad to purchase praise and gratitude by Scotch and Irish airs, at the resquest of her younger sisters, who with some of the Lucases and two or three officers joined eagerly in dancing at one end of the room.
What do the lines in bold mean?