“We simply cannot believe Jefferson’s complaints about his slaves, which fit into his pattern of shifting blame to others for his own mistakes and weaknesses. During his presidency Jefferson averred that the slave’s “burden on his master [is] daily increasing,” yet as the economic historian Steven Hochman has found, “during his presidency Jefferson’s nailery and his farms provided an income that should have met reasonable expectations. The debit side of Jefferson’s balance sheet was where he had his problems”