句子下面的讲解很详细，你可能没注意。
中间并列的 and music very great 是个省略句。下面是这个句不省略的完整结构（括号中是原句的省略部分）：
Formaly, too, pictures had given him considerable (delight) and music (had given him) very great delight.
可见，第一分句 pictures had given him 和 mucic had given him 的直接宾语都是 delight，只不过第一个是 considerable delight , 第二个是 great delight。由于第一个把 delight 省略了， 为了避免只被看做是第二句的宾语，所以就把第二个省略句 music very great 前后都用逗号隔开了。
