The sort of dependence that results from exchange, i.e., from commercial transactions, is a reciprocal dependence. We cannot be dependent upon a foreigner without his being dependent on us. Now, this is what constitutes the very essence of society. To sever natural interrelations is not to make oneself independent, but to isolate oneself completely.
– Frédéric Bastiat

This is not an argument against severing unnatural or unbalanced relations (such as our disproportionate financial contributions to the European Union in return for an avalanche of dirigiste regulations) back to a more sustainable and amenable level.
His argument assumes that all relations are equal.
No; but he does assume they are relations capable of breach. Dependency becomes invisible when it is certain.
Well said, Guy. Bastiat was not talking about state-to-state relationships, which are perverse by their very nature. He was talking about not preventing people from trading with each other regardless of where they are, which is the opposite notion to ‘Britain trades with the EU’… it does nothing of the sort. Individuals and companies trade with individuals and companies and must be allowed to do so unfettered.