"Political economists say that capital sets towards the most profitable trades, and that it rapidly leaves the less profitable and non-paying trades. But in ordinary countries this is a slow process, and some persons who want to have ocular demonstration of abstract truths have been inclined to doubt it because they could not see it. In England, however, the process would be visible enough if you could only see the books of the bill brokers and the bankers. Their bill cases as a rule are full of the bills drawn in the most profitable trades, and caeteris paribus and in comparison empty of those drawn in the less profitable. If the iron trade ceases to be as profitable as usual, less iron is sold; the fewer the sales the fewer the bills; and in consequence the number of iron bills in Lombard Street is diminished. On the other hand, if in consequence of a bad harvest the corn trade becomes on a sudden profitable, immediately 'corn bills' are created in great numbers, and if good are discounted in Lombard Street. Thus English capital runs as surely and instantly where it is most wanted, and where there is most to be made of it, as water runs to find its level.
"This efficient and instantly-ready organisation gives us an enormous advantage in competition with less advanced countries--less advanced, that is, in this particular respect of credit. In a new trade English capital is instantly at the disposal of persons capable of understanding the new opportunities and of making good use of them. In countries where there is little money to lend, and where that little is lent tardily and reluctantly, enterprising traders are long kept back, because they cannot at once borrow the capital, without which skill and knowledge are useless...
"But in exact proportion to the power of this system is its delicacy I should hardly say too much if I said its danger. Only our familiarity blinds us to the marvellous nature of the system. There never was so much borrowed money collected in the world as is now collected in London. Of the many millions in Lombard Street, infinitely the greater proportion is held by bankers or others on short notice or on demand; that is to say, the owners could ask for it all any day they please: in a panic some of them do ask for some of it. If any large fraction of that money really was demanded, our banking system and our industrial system too would be in great danger."
Walter Bagehot, Lombard Street (1873)