Lloyd Blankfein. | REUTERS/Jason Reed Things were going very well for Goldman Sachs, for the J Aron division, and for me at the firm. At the end of 1990, John Weinberg retired, and Bob Rubin and Steve Friedman became co-senior partners and co-chairs of the management committee. That was all as anticipated. Less expected was when Rubin left two years later to become chair of President Clinton’s newly created National Economic Council. Part of the idea of having co-heads was to create a balance be...