Would you believe it, dear friend, from these gloomy thoughts and apparent contradictions, there was shaped in my mind the sublime idea of the soul, which all my seeking had hitherto failed to discover?  While I meditated upon man’s nature, I seemed to discover two distinct principles in it; one of them raised him to the study of the eternal truths, to the love of justice, and of true morality, to the regions of the world of thought, which the wise delight to contemplate; the other led him downwards to himself, made him the slave of his senses, of the passions which are their instruments, and thus opposed everything suggested to him by the former principle.  When I felt myself carried away, distracted by these conflicting motives, I said, No; man is not one; I will and I will not; I feel myself at once a slave and a free man; I perceive what is right, I love it, and I do what is wrong; I am active when I listen to the voice of reason; I am passive when I am carried away by my passions; and when I yield, my worst suffering is the knowledge that I might have resisted.

Young man, hear me with confidence.  I will always be honest with you.  If conscience is the creature of prejudice, I am certainly wrong, and there is no such thing as a proof of morality; but if to put oneself first is an inclination natural to man, and if the first sentiment of justice is moreover inborn in the human heart, let those who say man is a simple creature remove these contradictions and I will grant that there is but one substance.

You will note that by this term ‘substance’ I understand generally the being endowed with some primitive quality, apart from all special and secondary modifications.  If then all the primitive qualities which are known to us can be united in one and the same being, we should only acknowledge one substance; but if there are qualities which are mutually exclusive, there are as many different substances as there are such exclusions.  You will think this over; for my own part, whatever Locke may say, it is enough for me to recognise matter as having merely extension and divisibility to convince myself that it cannot think, and if a philosopher tells me that trees feel and rocks think [Footnote:  It seems to me that modern philosophy, far from saying that rocks think, has discovered that men do not think.  It perceives nothing more in nature than sensitive beings; and the only difference it finds between a man and a stone is that a man is a sensitive being which experiences sensations, and a stone is a sensitive being which does not experience sensations.  But if it is true that all matter feels, where shall I find the sensitive unit, the individual ego?  Shall it be in each molecule of matter or in bodies as aggregates of molecules?  Shall I place this unity in fluids and solids alike, in compounds and in elements?  You tell me nature consists of individuals.  But what are these individuals?  Is that stone an individual or an aggregate of individuals?  Is