Among the best known Polish Romantics are the "Three Bards" – the three national poets active in the age of foreign partitions – Adam Mickiewicz, Juliusz Słowacki and Zygmunt Krasiński. The narrative poem ''Pan Tadeusz'' by Mickiewicz is Poland's national epic and a compulsory reading (''lektura'') in the country's schools. Joseph Conrad, the son of dramatist Apollo Korzeniowski, came to fame with his English-language novels and stories that are informed with elements of the Polish national experience. Conrad's ''Heart of Darkness'', ''Nostromo'' and ''Lord Jim'' are believed to be one of the finest works ever written, placing him among the greatest novelists of all time. Modern Polish literature is versatile, with its fantasy genre having been particularly praised. The philosophical sci-fi novel ''Solaris'' is an acclaimed example of Stanisław Lem's literary legacy, whereas ''The Witcher'', a fantasy series by Andrzej Sapkowski, is a much-celebrated work of contemporary Polish fiction.