from politics to physics. The significant thing about such influences, where they are relevant, is what the artists did with them. Materials and techniques, varying with different periods, may have provided common limiting conditions, class and personal associations may have furnished the ideals and allegiances determining the selection of themes, but what marks the unique achievement of the great artist is his individual craftsmanship, his sensibility, insight, and power to make us see things in a fresh light.
It is often alleged that in painting, as in music and literature, the great artist meets the need or atmosphere of his time which, in a sense, speaks through him even when he is unconscious of it or in revolt against it. Even if this were true the great artist would prove himself in how he meets that need, not merely in being a creature of it. But it is not always true. Very often the great creator runs counter to the modes of feeling and understanding around him. He has to rely upon his own work ultimately to generate the taste and sensibility which are capable of appreciating his intent and the skill of his execution. One need but read the excommunications pronounced by shocked critics against new departments in the history of art and music to realize to what an extent public taste is gradually transformed by those who have begun by outraging it.
The history of philosophy reflects the history of politics, religion, and science, but no one can make it intelligible without making central in his account the ideas of Socrates, Plato, Aristotle, Plotinus, Aquinas, Descartes, Spinoza, Leibnitz, Locke, Berkeley, Hume, Kant, and Hegel, to stop with the early nineteenth century. Sociological interpretations of philosophy have been unduly neglected, but what they explain is why certain ideas have been accepted within a particular milieu, not why they have been generated. The influential philosophies which succeed in getting themselves institutionalized are far fewer than the total number projected.
Sometimes ideas that make little headway in their own times, outside the narrow confines of a school, are revived in subsequent periods and used as a leverage to bulwark social power or pry it loose from entrenched positions. If such occasions never arise, these ideas remain enshrined in the great works of philosophy and are sources of perennial interest to lonely and questing spirits in every climate of opinion. Despite the local idiom and emphasis with which they are clothed, certain recurrent themes
