""Mr. Jefferson displays a mild, easy and obliging temper," commented the duc de La Rochefoucald-Liancourt, "though he is somewhat cold and reserved. His conversation is the most agreeable kind." Jefferson was open and approachable, yet he maintained an impregnable core of inner feeling that has frustrated his biographers. He had an insatiable curiosity about all aspects of life. His fondness for structure and order can be seen in the meticulous records he maintained on plant life and weather conditions at Monticello. Despite his many years in politics, he never acquired two attributes usually considered essential to success in that profession: a thick skin and a gift for oratory. He was acutely sensitive to public criticism and, although captivating in small groups, delivered notoriously unmoving speeches before large crowds. He tended to mumble softly out of earshot of much of his audience."