Author of one of the first Polish–language monuments of memoir literature on the territory of Belarus. In 1625–1631, he kept a diary (Diariusz) depicting events from 1594 to 1621, including the
Time of Troubles in Russia, the accession of
False Dmitry I, the
Russian–Polish War (1609–1618) and the
Polish–Ottoman War (1620–1621), as well as the
Battle of Tsetsora. Maskiewicz's diaries describe in detail the
Siege of Smolensk (1609–1611), while emphasizing the courage of the city's defenders, especially its governor
Mikhail Shein. The actions of the commanders of the Commonwealth, including Stanisław Żółkiewski, were critically assessed; a significant place in the work is occupied by a description of the life of the Moscow
boyars, their opinions about the Polish gentry liberties, as gentry willfulness, are positively evaluated. The author justifies the harsh reaction of the Russian peasantry against the troops of the Commonwealth, as revenge for the disasters it inflicted on the people. He also owns the notes placed, in Russian translation, in the collection of
Nikolai Ustryalov "Legends of Contemporaries About Dmitry the Pretender". Maskiewicz did not touch on the issues of big politics in the Diaries. In addition to military and political events, he described in his diary a comparison of Polish and Russian culture. The diary is written in the style of
gawęda szlachecka ("noble storytelling"). ==Family==