In the case of the _Descent from the Cross_ we have already hinted at the power of tone to arouse emotion. I may add that tone always makes a strong appeal to feeling--to abstract feeling. The tonal harmony of an opal, whose pinks and greens are suffused with creamy atmosphere, arouses in us delight, quite apart from any suggestion to our mind. The delight is one of pure feeling. Can you not see that, if an artist uses the tonal harmony of the opal as a color scheme for a picture, the harmony would still delight us in an abstract way? It would be interwoven now with the subject of his picture, and we need not try, nor do we wish to separate them. But the sentiment of the figure or the scene will be all the more tender and lovely for the harmony with which it is suffused.