Jefferson said slavery was a complex issue and needed to be solved by the next generation. Jefferson wrote that the Missouri Compromise was a "fire bell in the night" and "the knell of the Union". Jefferson said that he feared the Union would dissolve, stating that the "Missouri question aroused and filled me with alarm." In regard to whether the Union would remain for a long period of time Jefferson wrote, "I now doubt it much." In 1823, in a letter to Supreme Court Justice William Johnson, Jefferson wrote “this case is not dead, it only sleepeth. the Indian chief said he did not go to war for every petty injury by itself; but put it into his pouch, and when that was full, he then made war.” In 1798, Jefferson's friend from the Revolution, Tadeusz Kościuszko, a Polish nobleman and revolutionary, visited the United States to collect back pay from the government for his military service. He entrusted his assets to Jefferson with a will directing him to spend the American money and proceeds from his land in the U.S. to free and educate slaves, including Jefferson's, and at no cost to Jefferson. Kościuszko revised will states: "I hereby authorise my friend Thomas Jefferson to employ the whole thereof in purchasing Negroes from among his own or any others and giving them Liberty in my name." Kosciuszko died in 1817, but Jefferson never carried out the terms of the will: At age 77, he pleaded an inability to act as executor due to his advanced age and the numerous legal complexities of the bequest—the will was contested by several family members and was tied up in the courts for years, long after Jefferson's death. Jefferson recommended his friend John Hartwell Cocke, who also opposed slavery, as executor, but Cocke likewise declined to execute the bequest. In 1852 the U.S. Supreme Court awarded the estate, by then worth $50,000, to Kościuszko's heirs in Poland, having ruled that the will was invalid. Jefferson continued to struggle with debt after serving as president. He used some of his hundreds of slaves as collateral to his creditors. This debt was due to his lavish lifestyle, long construction and changes to Monticello, imported goods, art, and lifelong issues with debt, from inheriting the debt of father-in-law John Wayles to signing two 10,000 notes late in life to assist dear friend Wilson Cary Nicholas, which proved to be his coup de grace.