Acting on an idea from the poet Johann von Goethe, in 1820 Friedrich Ferdinand Runge first isolated caffeine as the cause of insomnia in coffee drinkers. Initial attempts at decaffeinating coffee involved applying solvents to already roasted coffee beans. While it was easier to remove the caffeine from a roasted bean (the solvents did not adequately penetrate unroasted beans), the flavor and aroma were also adversely affected. In subsequent efforts, green coffee beans were broken or ground so that the solvents could better extract the caffeine. However, pre-ground coffee proved too difficult to roast adequately.