Amartya Sen in the NYRB:
[E]ven as the positive contributions of capitalism through market processes were being clarified and explicated, its negative sides were also becoming clear—often to the very same analysts. While a number of socialist critics, most notably Karl Marx, influentially made a case for censuring and ultimately supplanting capitalism, the huge limitations of relying entirely on the market economy and the profit motive were also clear enough even to Adam Smith. Indeed, early advocates of the use of markets, including Smith, did not take the pure market mechanism to be a freestanding performer of excellence, nor did they take the profit motive to be all that is needed.
Even though people seek trade because of self-interest (nothing more than self-interest is needed, as Smith famously put it, in explaining why bakers, brewers, butchers, and consumers seek trade), nevertheless an economy can operate effectively only on the basis of trust among different parties. When business activities, including those of banks and other financial institutions, generate the confidence that they can and will do the things they pledge, then relations among lenders and borrowers can go smoothly in a mutually supportive way. As Adam Smith wrote:
When the people of any particular country have such confidence in the fortune, probity, and prudence of a particular banker, as to believe that he is always ready to pay upon demand such of his promissory notes as are likely to be at any time presented to him; those notes come to have the same currency as gold and silver money, from the confidence that such money can at any time be had for them.
Smith explained why sometimes this did not happen, and he would not have found anything particularly puzzling, I would suggest, in the difficulties faced today by businesses and banks thanks to the widespread fear and mistrust that is keeping credit markets frozen and preventing a coordinated expansion of credit.