It is not possible, I think, to rise from the perusal of the arguments of Clark and Spinoza without a deep conviction of the futility of all endeavor… - Benedictus de Spinoza

Benedict Spinoza teaches: there is only one substance, and that is God. This one substance is infinite; it is absolute. All finite substances originate from it, are contained in it, arise out of it, are immersed in it; they have only a relative, transient, accidental existence. The absolute substance is revealed to us both in the form of infinite thought and in the form of infinite dimension. These two, infinite thought and infinite dimension, are the two attributes of the absolute substance. We recognize only these two attributes, but it is possible that God, the absolute substance, has other attributes that we do not know. "Non dico, me deum omnino cognoscere, sed me quaedam ejus attributa, non autem omnia, neque maximam intelligere partem." Only stupidity and malice could attach to this doctrine the epithet "atheistic." No one has ever spoken more sublimely of the Deity than Spinoza. Instead of saying that he denied God, one might say that he denied man. All finite things are to him only modi of the infinite substance. All finite things are contained in God; the human mind is but a light‑ray of infinite thought; the human body is but a particle of the infinite dimension. God is the infinite cause of both, of spirits and of bodies, natura naturans.

...I depart tonight to spend a few days in Münster and am on that account very busy and distracted, else I would be writing more as to the possible advantages there might be in presenting to the public Spinoza's system in its true form and according to the intrinsic coherence of its parts. Its spectre has been haunting Germany for lo these many years, in all shapes and sizes and is regarded with reverence by believers and doubters alike. I am speaking not just of the petty-minded but of people with the finest minds.

men are
mistaken in thinking themselves free; their opinion is made up
of consciousness of their own actions, and ignorance of the
causes by which they are conditioned. Their idea of freedom,
therefore, is simply their ignorance of any cause for their
actions. As for their saying that human actions depend on the
will, this is a mere phrase without any idea to correspond
thereto. What the will is, and how it moves the body, they none
of them know; those who boast of such knowledge, and feign
dwellings and habitations for the soul, are wont to provoke
either laughter or disgust. So, again, when we look at the sun,
we imagine that it is distant from us about two hundred feet;
this error does not lie solely in this fancy, but in the fact
that, while we thus imagine, we do not know the sun's true
distance or the cause of the fancy. For although we afterwards
learn, that the sun is distant from us more than six hundred of
the earth's diameters, we none the less shall fancy it to be near;
for we do not imagine the sun as near us, because we are
ignorant of its true distance, but because the modification of
our body involves the essence of the sun, in so far as our said
body is affected thereby.