 The emergence of new philosophical systems results on this view from a necessity that is both internal and external. Certain philosophical ideas are only capable of achieving historical expression under specific historical conditions. Just as it was only possible for Christianity to appear at that point in history when the ties of family and nation in Greco-Roman antiquity were dissolved, so it was only possible for modern philosophy to appear under specific historical conditions. The beginning of the history of modern philosophy must be located at the point at which the modern spirit first begins to distinguish itself from the medieval spirit. The dominant principle of the medieval period was the Judeo-Christian, monotheistic principle, according to which God is conceived as an omnipotent person through an act of whose will the material world was created from nothing (ex nihilo). It is because nature, as conceived from this standpoint, is excluded from the divine substance, according to Feuerbach, that medieval thought showed no interest in the investigation of nature. It is only where the substantiality of nature begins to be rediscovered that the spirit of modernity distinguishes itself from the medieval spirit. This occurs most clearly where matter comes to be regarded as an attribute of the divine substance, so that God is no longer conceived of as a being distinct from nature but rather as the immutable and eternal imminent cause from which the plenitude of finite shapes in nature pours forth. This happens first among the nature philosophers of the Italian Renaissance, and subsequently in the speculative reflections of Jakob Böhme and in the system of Spinoza. Indeed, it is one distinctive feature of Feuerbach’s view of the history of modern philosophy that he thinks of it as beginning, not with Descartes, but with the nature philosophers of the Italian Renaissance. Feuerbach insists upon the speculative significance of Bacon’s philosophy of nature. It is precisely in subjecting nature to experimentation, and thereby to rational comprehension, that spirit raises itself above nature. But while Feuerbach emphasizes the philosophical importance of experience in the modern rediscovery of nature, he nevertheless insists that empiricism lacks a “principle” of its own. Later he will speak of the need for an alliance between German metaphysics and “the anti-scholastic, sanguine principle of French sensualism and materialism” (VT 254–255/165).