The author of the Declaration of Independence and surely our most "intellectual" president, Thomas Jefferson, wrote that we have life and liberty for the pursuit of happiness. In his private letters, Jefferson carefully distinguished between the modern, individualistic life devoted to the pursuit of happiness and happiness itself. He found in human beings two sources of happiness.
The first flows from the human mind and was most perfectly described the philosopher Epicurus.
The second flows from the "instinct" or "moral sense" nature gives us as social animals. The moral doctrine that corresponds to that sense was most perfectly described by Jesus.
Because we are neither pure minds nor merely instinct-driven animals, neither Epicurus nor Jesus, by himself, is enough. That's why Jefferson actually described himself as a Christian Epicurean.
Jefferson explained that the that Epicurean philosophers found happiness through their unflinching acceptance of the truth of atheistic materialism, and so in their capacity to live truthfully beyond hope and fear—the twin sources of the miserable restlessness specific to self-conscious mortals. That's the restlessness, of course, that's been intensified in the modern, middle-class, techno-energized world.
The philosopher has (as they say on Seinfeld) "serenity now" because he knows that there's no hope that human beings can escape their natural mortality (which they, of course, share with the other animals). He also knows that it's unreasonable to fear death. We know nothing of being dead, and it doesn't make sense to fear what we can't know.
The Epicurean even knows that self-conscious mortality is the condition of philosophizing, of the intellectual pleasure given to members of our species alone of seeing things as they really are. That happy combination of serenity and pleasure comes from the philosopher, as Socrates first said, learning how to die. He (or she) learns to get over the ridiculous self-obsession that flows from unreasonable hopes and fears. (Transhumanists take note.)
So why can't we all just be Epicureans? According to Jefferson, that kind of intellectual liberation will never be available to most people. It requires considerable leisure, extraordinary education, and rare intellectual abilities.
Epicureans are also selfish; they're short on real emotional attachments to most people. They tend to limit their circle of concern to their philosopher-friends. Charity or even compassion that leads to social or personal service aren't virtues often found among the more intellectually detached.
Socrates, we remember, wasn't much of a family man. A species full of Epicureans wouldn't have much of a future.
That's why Jefferson turned to Jesus. And I will do that in the next post.