Any theory intended to describe and analyze socio-historical reality cannot restrict itself to the human spirit and disregard the totality of human nature.

On the other hand, for the whole human being who wills, feels, and represents, external reality is given simultaneously and with as much certitude as his own self.

In the real life-process, willing, feeling, and thinking are only different aspects.

If we conceive all the changes in the physical world as reducible to the motion of atoms, motions generated by means of the fixed nuclear forces of those atoms, the whole of the world could thus be known by means of the natural sciences.

A knowledge of the forces that rule society, of the causes that have produced its upheavals, and of society's resources for promoting healthy progress has become of vital concern to our civilization.

No real blood flows in the veins of the knowing subject constructed by Locke, Hume, and Kant, but rather the diluted extract of reason as a mere activity of thought.

The existence of inherent limits of experience in no way settles the question about the subordination of facts of the human world to our knowledge of matter.