The Works of Benedictus de Spinoza

...of immanent emanations. And there is indeed a reason why such a reduction of all finite things to an infinite unity appeals so greatly to the intellect or logical faculty. The act of thinking, to be sure, consists solely in the thinking subject perceiving the unity of things that are different in another respect, or even potentially most diverse. a is predicated of b, insofar as it is understood that a is inherent in b in that very sense which is the subject of inquiry. Whence it is clear, and has long been shown, that the formal or logical investigation of truth is to be compared with arithmetical permutation, whereby two numbers appearing under a different guise are and remain the same, such as 2 x 3 = 6. It follows spontaneously that in that very formal investigation of truth, there can be no higher canon than this: that multiple things must always be reduced to one. From this, thinking beings neither cease nor can they define the limit of their efforts, not only in raising individuals to species, or species to general classes, but also in referring all derived principles or applied laws to one principle in thought and deducing them from there. Nor is it difficult to understand that everything about which thought is occupied—what they call the object—can be reached and treated by thinking and willing, not insofar as it exists outside of thought, but insofar as it is present to the mind (whether as an existing thing or as something merely thinkable), or rather, is now an inherent part of the mind. Whence, if the thinker is called the subject, it becomes clear that he himself, while he thinks, is entirely a subject-object, or that one source of the subjective and objective...