The article presents personality and activities of Augustyn Middleton, nobleman from Kaunas powiat, with the main focus on assessing this person in the light of political events in the Polish-Lithuanian Commonwealth and the geopolitical situation. At the centre of this research is the period from the reinstatement of the diplomatic mission of the Commonwealth in The Hague on 14 April 1790 to the end of activities of the Four-Year Sejm. The article reveals that Augustyn Middleton, assigned by Stanislaw August to the diplomatic mission of the Commonwealth in the United Provinces of the Netherlands, was the agent of the King, who had to inform the King’s cabinet on activities of Envoy Extraordinary and Minister Plenipotentiary Mihał Kleofas Ogiński and to promote the reforms by the Four-Year Sejm in the foreign press thus shaping a positive public opinion in Western Europe regarding changes in Poland and Lithuania. Due to benevolent circumstances A. Middleton was able to reach the rank of embassy resident, however the horizons of his diplomatic career were limited by available finances. Political views of A. Middleton reflected aims declared by the fraction of Stanislaw August’s court: to create a strong and prospering monarchy, hoping that the state will be able to regain its glorious past. A. Middleton promoted constitutional monarchy, inheritable throne, regulation of activities of the Sejm and the dietines (sejmiki), granting of political rights to townspeople, and economic development of the country. While supporting the idea of a centralized state, A. Middleton did not reflect on the rights of the Grand Duchy of Lithuania or the topic of a binary state. In assessing economic changes in Europe A. Middleton opposed the physiocrats, emphasizing that the most powerful form of capital comes not from agriculture but from banking. However, he was not afraid to admit that his knowledge of economics was not sufficient to explain the processes of financial capital. Ideas of religious tolerance, promoted by A. Middleton, his cosmopolite view of collaboration between states and nations, active interest in political and social transformations in Europe through anonymous polemical publications in foreign press on the topics of revolution allow for bringing the nobleman from Kaunas powiat A. Middleton into the circle of yet unknown people of the Enlightenment.