At the same time, while observation becomes more difficult, it is more carelessly and badly done; this is another reason for the small success of our researches into the natural history of the human race.  The information acquired by travel depends upon the object of the journey.  If this object is a system of philosophy, the traveller only sees what he desires to see; if it is self-interest, it engrosses the whole attention of those concerned.  Commerce and the arts which blend and mingle the nations at the same time prevent them from studying each other.  If they know how to make a profit out of their neighbours, what more do they need to know?

It is a good thing to know all the places where we might live, so as to choose those where we can live most comfortably.  If every one lived by his own efforts, all he would need to know would be how much land would keep him in food.  The savage, who has need of no one, and envies no one, neither knows nor seeks to know any other country but his own.  If he requires more land for his subsistence he shuns inhabited places; he makes war upon the wild beasts and feeds on them.  But for us, to whom civilised life has become a necessity, for us who must needs devour our fellow-creatures, self-interest prompts each one of us to frequent those districts where there are most people to be devoured.  This is why we all flock to Rome, Paris, and London.  Human flesh and blood are always cheapest in the capital cities.  Thus we only know the great nations, which are just like one another.

They say that men of learning travel to obtain information; not so, they travel like other people from interested motives.  Philosophers like Plato and Pythagoras are no longer to be found, or if they are, it must be in far-off lands.  Our men of learning only travel at the king’s command; they are sent out, their expenses are paid, they receive a salary for seeing such and such things, and the object of that journey is certainly not the study of any question of morals.  Their whole time is required for the object of their journey, and they are too honest not to earn their pay.  If in any country whatsoever there are people travelling at their own expense, you may be sure it is not to study men but to teach them.  It is not knowledge they desire but ostentation.  How should their travels teach them to shake off the yoke of prejudice?  It is prejudice that sends them on their travels.

To travel to see foreign lands or to see foreign nations are two very different things.  The former is the usual aim of the curious, the latter is merely subordinate to it.  If you wish to travel as a philosopher you should reverse this order.  The child observes things till he is old enough to study men.  Man should begin by studying his fellows; he can study things later if time permits.