But a far wider significance than is thus indicated, is conveyed by the necessity for generalizing expression in order to reach the painter's ideal. It has already been noted that inasmuch as all men have the same general idea of beauty--that they generally agree as to what is, or is not, beautiful, it follows that there must be a common opinion as to degrees of beauty, and so a universality of ideal; that is of course, among people with similar experience of life, as for instance the white races of the world.[49] Hence the ideals of all painters must be similar. They must necessarily aim for the same generalization--exclude or emphasize like. Manner or style, or national type may vary; purely sensorial effects may differ as the minds of the painters have been variously trained, but the combination of features and effects which regulate the expression will be practically identical in every realized ideal. Consequently, subject to changes in attitude or age, ideal heads of all artists are interchangeable without incongruity resulting, irrespective of the motive of the design, for the ideal countenance indicated adapts itself to any character where no emotional or passionate expression is required. The head of the figure representing "Profane Love" in Titian's great picture, would serve to express spiritual nobility in a Madonna,[a] and when a head in a Madonna by Raphael is exchanged with that of the central figure in Fragonard's The Pursuit,[b] there is no resulting suggestion of impropriety in either picture.[c] Ideal countenances have sometimes been given to evil characters, as in Luini's Salome,[d] and the head in this picture would equally well serve for a Madonna.[e] [a] See Plate 9. [b] Frick Collection, New York.[50] [c] See Plate 8. [d] Uffizi Gallery, Florence. [e] See Plate 10. An ideal head then will suggest any expression that the design in which it is included seems to require, subject to the restrictions before noted. In The Pursuit the face of the woman presumed to be fleeing from her lover indicates some concern, and even a little fear,[a] but that this is due to the surroundings in the work, is shown when the head is substituted for another in a different picture, for the concern has disappeared, and the expression becomes one which may properly represent the highest attributes connected with the Madonna. [a] See Frontispiece and Plate 11.