Why are great men rarely chosen president?

When looking over the candidates during most presidential elections, we often ask ourselves, "Is this the best we can produce?" Although the Republicans are taking mediocrity to new heights this time around, Democrats have generally done no better in the recent past (2008 excepted). It's easy to conclude that "Rome is Burning" and America is in headlong decline. Cheer up. This is nothing new. In his famous 1888 book "The American Commonwealth," British historian James Bryce wrote: "Europeans often ask ... how it happens that this great office, the greatest in the world -- is not more frequently filled by great and striking men. ... The ordinary American voter does not object to mediocrity. ... He likes his candidate to be sensible, vigorous, and, above all, what he calls 'magnetic,' and does not value, because he sees no need for, originality or profundity, a fine culture or a wide knowledge. Candidates are selected to be run for nomination by knots of persons who, however expert as party tacticians, are usually commonplace men; and the choice between those selected for nomination is made by a very large body, an assembly of nearly a thousand delegates from the local party organizations over the country, who are certainly no better than ordinary citizens." At the time, Bryce was bemoaning the likes of James K. Polk and Franklin Pierce, two of our eminently forgettable presidents. But he captures our modern body politic as well (think Michael Dukakis or Michele Bachmann). In short, plus ça change, plus c'est la même chose.