We must admit that grand conceptions of concrete unity are to be found here， as opposed to the abstract metaphysical determinations of the understanding， e.g.， the fruitfulness of Nature. But， on the other hand， the point of most importance with these philosophers is that what is to be accepted as valid must have presence， and that man in all knowledge must be himself the knower； for， as we may see， those philosophers made war on all external authority of state and church， and in particular on abstract thought which has no present meaning in us. Two determinations found in all philosophy are the concretion of the Idea and the presence of the spirit in the same； my content must at the same time be something concrete， present. This concrete was termed Reason， and for it the more noble of those men contended with the greatest enthusiasm and warmth. Thought was raised like a standard among the nations， liberty of conviction and of conscience in me. They said to mankind， “In this sign thou shalt conquer，” for they had before their eyes what had been done in the name of the cross alone， what had been made a matter of faith and law and religion - they saw how the sign of the cross had been degraded. For in the sign of the cross lying and deceit had been victorious， under this seal institutions had become fossilised， and had sunk into all manner of degradation， so that this sign came to be represented as the epitome and root of all evil. Thus in another form they completed the Reformation that Luther began. This concrete had manifold forms； social instincts in the practical sphere， laws of nature in the theoretical. There is present the absolute impulse to find a compass immanent in themselves， i.e. in the human mind. For the human mind it is imperative to have a fixed point such as this， if， indeed， it is to be within itself， if it is to be free in its own world at least. But this striving after really present vitality took forms which as by-paths were themselves one-sided. In this striving after unity， which was， however， concrete unity， the further varieties of the content likewise lie.
On the theoretic side of their philosophy， therefore， the French proceeded to materialism or naturalism， because the requirements of the understanding， as abstract thought， which from a firmly fixed principle allows the most monstrous consequences to be drawn， drove them to set up one principle as ultimate， and that a principle which had at the same time to be present and to lie quite close to experience. Hence they accept sensation and matter as the only truth， to which must be reduced all thought， all morality， as a mere modification of sensation. The unities which the French propounded were in this way one-sided.
a. OPPOSITION OF SENSATION AND THOUGHT.
To this one-sidedness belongs the opposition between sentir and penser， or else， if you like， their identity， making the latter only a result of the former； there is not， however， any speculative reconciliation of this opposition in God， such as we find in Spinoza and Malebranche. This reduction of all thought to sensation， which in certain respects took place with Locke， becomes a widely extended theory. Robinet (De la Nature， T. I. P. IV. chap. iii. pp. 257-259) lights also on this opposition， beyond which he does not get， that mind and body are not separate， but that the manner in which they are united is inexplicable. The Système de la Nature (T. I. chap. x. p. 177)is marked by an especially plain reduction of thought to sensation. The leading thought is this：
“Abstract thoughts are only modes in which our inmost organ views its own modifications. The words goodness， beauty， order， intelligence， virtue， &c.， have no meaning for us if we do not refer and apply them to objects which our senses have shown to be capable of these qualities， or to modes of being and acting which are known to us.” Thus even psychology passed into materialism， as for instance we may find in La Mettrie's work L'homme Machine： All thought and all conception have meaning only if they are apprehended as material； matter alone exists.
b. MONTESQUIEU.
Other great writers have opposed to the above the feeling in the breast， the instinct of self-preservation， benevolent dispositions towards others， the impulse to fellowship， which last Puffendorf also made the foundation of his system of law (supra， p. 321). From this point of view much that is excellent has been said. Thus Montesquieu， in his charming book， L'Esprit des Lois， of which Voltaire said it was an esprit sur les lois， regarded the nations from this important point of view， that their constitution， their religion， in short， everything that is to be found in a state， constitutes a totality.
c. HELVETIUS.
This reduction of thought to feeling in the case of Helvetius takes the form that if in man as a moral being a single principle is sought， this ought to be called self-love， and he endeavoured to demonstrate by ingenious analysis that whatever we term virtue， all activity and law and right， has as its foundation nothing but self-love or selfishness， and is resolvable thereinto.(8) This principle is one-sided， although the “I myself” is an essential moment. What I will， the noblest， the holiest， is my aim； I must take part in it， I must agree to it， I must approve of it. With all self-sacrifice there is always conjoined some satisfaction， some finding of self； this element of self， subjective liberty， must always be present. If this is taken in a one-sided sense， there may be consequences drawn from it which overthrow all that is sacred； but it is found in equal degree in a morality as noble as any possibly can be.
d. ROUSSEAU.
