Usbek to *** 
A clever man is ordinarily difficult in company. He chooses few persons ; he is bored with that whole large number of people whom he likes to call bad company. He cannot prevent communicating some of his distaste : so many enemies.
Sure to please when he wishes, he often neglects to do so.
He is inclined to criticism, because he sees more things than another, and has a better sense of them.
He almost always ruins his fortune, because his mind provides him with a larger number of means of doing that.
He fails in his enterprises, because he risks much. His eyesight, which always carries far, lets him see objects that are too far away. Not to mention that, in the conception of a project, he is less struck by the difficulties that come from the thing itself, than of the remedies that are his own, and which he draws from his own resources.
He neglects the small details, on which however depends the success of almost all great matters.
The mediocre man, on the contraire, seeks to take advantage of everything : he is quite aware that he must not lose anything by neglect.
Unanimous approval is more ordinarily for the mediocre man. To him one gives cheerfully ; from the other one is delighted to take. While envy swoops down on the one, and nothing is forgiven him, the other is complement in every way ; vanity declares for him.
But if a clever man has so many disadvantages, what shall we say of the harsh situation of scholars ?
I never think of them without remembering a letter from one of them to a friend of mine. Here it is :
I am a man who spends every night watching with thirty-foot spy glasses those great bodies that orbit overhead : and when I want to relax, I take my little microscopes and observe a vermin or a mite. 
I am not rich, and have but one room. I dare not even make a fire here, because I keep my thermometer here, and the external heat would make it rise. Last winter I nearly died of cold ; and though my thermometer, which was as low at it could go, warned me that my hands were going to freeze, I took no action. And I have the consolation of being exactly informed about the most imperceptible changes in the weather all last year.
I have very little contact ; and of all the people I see, I know not a one. But there is a man in Stockholm, another in Leipsig, and another in London, whom I have never seen, and will no doubt never see, with whom I carry on such a regular correspondence that I never let a mailing go by without writing to them. 
But although I know no one in my neighborhood, I am in such poor reputation here that I will ultimately be obligated to move away. Five years ago I was crudely insulted by a neighbor for having performed a dissection on a dog which, she claimed, belonged to her. A butcher’s wife, who was present, joined the fray. And while the former was showering me with insults, the latter was throwing stones at me, as well as at Dr. ***, who was with me, and who took a terrible blow on the frontal and occipital bone, greatly shaking the seat of his reason.
Since that time, as soon as some dog down the street goes astray, it is at once decided that I have had a hand in it. A good bourgeoise who had lost a small one, which she loved, she said, more than her children, came the other day and fainted in my room ; and not finding it, she summoned me before the magistrate. I believe I shall never be delivered from the importunate malice of these women who, with their yapping voices, are constantly deafening me with the funeral oration of all the automata  that have died in the last ten years.
I am, etc.
All scholars were formerly accused of sorcery. This does not surprise me. Everyone said to himself : I have taken natural talents as far as they can go, yet a certain scholar has advantages over me ; there must be some devilry mixed up in it.
Now that these sorts of accusations have fallen into disrepute, they have taken another tack, and a scholar cannot avoid the reproach of irreligion or heresy. Even if he is absolved by the people, the wound is there, and will never really heal ; it is always for him a sore spot. An adversary will come thirty years later, and say to him modestly : God forbid I should say that what you are accused of is true, but you were obliged to defend yourself. In this way they turn even his justification against him.
If he writes some history, and has some nobility of mind and some rectitude in his heart, they drum up a thousand persecutions for him. They will go rouse the magistrate against him over an incident that took place a thousand years ago.  And they will want his pen to be captive if it is not venal.
Happier nevertheless than these cowardly men who abandon their faith for a modest stipend ; who, to take all their impostures in detail, sell them for not even a halfpenny ; who overturn the constitution of the empire, diminish the rights of an authority, increase those of another, give to princes, take away from peoples, revive elapsed rights, flatter the passions most in vogue in their time, and the vices that are on the throne ; deceive posterity all the more unworthily that it has fewer means of detroying their testimony. 
But it is not enough that an author have suffered all these insults ; it is not enough for him to have been in continual anxiety over the reception of his book. It comes out finally, this book that has cost him so much. It attracts quarrels on every side. And how can he avoid them ? He had an opinion ; he supported it with his writings ; he did not know that a man two hundred leagues away had said exactly the opposite. Yet now war is being declared.
Even then, if he could have hoped to obtain some consideration ! No. He is at best esteemed by those who have applied themselves to the same science as he. A philosopher has a sovereign disdain of a man whose head is full of facts ; he is in turn regarded as a visionary by the man who has a good memory.
As for those who profess an arrogant ignorance, they would like the whole human race to be buried in the oblivion where they themselves will be.
A man who lacks a talent consoles himself by disdaining it ; he removes the obstacle he encountered between merit and himself, and in that way finds himself on the same level as the man whose writings he fears.
Moreover, we must add, to an equivocal reputation, the privation of pleasures and the loss of health.
Paris this 26th day of the moon of Chahban 1720