What is the place of the attributes and modes in the all-embracing and real substance? As to the attributes, Spinoza maintained that we, as finite beings, do not know God in His character as substance, but that He always appears to us through His attributes of thought and extension. There are only these two attributes that the human mind can know, although God as an infinite being must possess an infinite number of such attributes. In our human world all things are either thought-things or extension-things. Each of these two attributes is infinite after its kind. Each fully expresses an aspect of God without depreciating the value of the other. Each is fully adequate, just as a table may be both white and hard without either quality infringing upon the other. The attributes are the substance made more concrete. The modes are in turn modifications of the attributes and more concrete expressions of them and of the substance. Each mode is infinite after its kind. Since God exists only in reality, He would not supposably see from His point of view the world laid out in attributes and modes; for these are only human ways of interpreting Him. While the critics agree that the modes are human interpretations of the attributes and therefore unreal, they disagree about the relation of the attributes to God. Some maintain that the attributes are merely human ways of seeing the substance, analogously to the modes――as if we saw God now as thought and now as extension; others maintain that God is nothing other than the sum of the attributes; of extension, thought, and the unknown, infinite, other attributes. The difficulty lays bare the nerve of the problem of pantheism, and probably Spinoza was not clear in his own mind about the relation of the attributes to the substance. Spinoza speaks more definitely upon this same problem of the relation of the modes to God. Is God the sum-total of all existent things, or is He the principle behind them? Spinoza says that God is both. God is the cause of the world, not cause in the way that the term is commonly used nor in the sense that Descartes used it. God is not to existent things the first cause or the unmoved mover of matter, or the teleological cause of thought, as in Descartes. He is cause in the sense that a triangle is the cause of its own three sides. He is the rational ground (_ratio essendi_) or the logical reason for the being of things. In this sense God may be regarded as the cause _both_ in the sense that He is the sum-total of existent things or modes (_natura naturata_), and in the sense that He is the immanent and energizing principle of existent things (_natura naturans_). These conceptions as well as their phrases Spinoza probably got from Bruno.