The King of Prussia to d'Alemhert
Potsdam, September 7, 1776.
Your letter, my dear d'Alembert, reached me on my re- tm-n from Silesia. I see that your tender heart is still sensitive, and I do not blame you. The powers of our souls have their limits, and we must exact nothing from them that is not possible. If a very strong and robust man were required to upset the Louvre by applying his shoulder, he could not do it ; but give him a stone of a hundred pounds to move, and the result is certain. It is the same thing with reason ; it can conquer obstacles proportioned to its strength, but there are others that force it to give way. Nature has made us feeling ; philosophy can never make us do the im- possible : and suppose it could, that would be harmful to society ; the result would be no compassion for the troubles of others ; the human species would end in becoming hard and pitiless. Eeason ought to serve us in moderating what- ever is excessive in us, but not in destroying the human being in the man.
Therefore regret your loss, my dear friend ; I will even add that the losses of friendship are irreparable ; and that whoever is capable of appreciating things as they are must judge you worthy of having true friends because you know how to love.
But as it is above the powers of man, and even of the gods, to change the past, you ought to try to preserve yourself for the friends who remain to you, in order not to cause them the mortal grief of losing you. I have had friends, both men and women ; I have lost five or six, and I thought to die of my grief. By a mere chance these losses fell upon me during the different wars in which I have been engaged, — a time in which I was continually obliged to
