Byron's other dramas depart farther than any of these, not only from fitness for the stage, but from likeness to any definite dramatic species. Of the four, however, all of which deal with a world of spirits, "Manfred" and "Cain" have tragic themes and protagonists. "It was," wrote Byron, "the Steinbach and the Jungfrau, and something else much more than Faustus that made me write Manfred." Nature, the ever-recurring theme of the romantic poets, is here given something akin to dramatic treatment. The impassioned descriptions create a presence, not one "that disturbs him with the joy of elevated thoughts," but "the wild comrade of Manfred's antipathy to men."[51] The mountains become sharers in the hero's tirades, though their nights' "dim and solitary loveliness" is the only power that curbs his fierce unrest. "Cain," less lyrical and far more distinct in its presentation of dramatic conflict, may rightly be claimed by romantic tragedy for its own. It is not merely Byron's own personality which finds expression here, but the revolt against convention and creed, so characteristic of the romantic movement. The demands of the individual man against society and providence make up the tragic theme. The tragedy of individual passion, leaping the bounds of history, romance, or actuality, is here divorced from the theatre, divorced indeed from any semblance to the models of tragedy; but in its symbolistic and allegorical presentation of philosophical questionings still keeps close to the essentials of great dramatic art, the searching of the motives and conflicts of human passion. Cain is of the brotherhood of Marlowe's Faustus and Shakespeare's Hamlet and other tragic heroes who chafe against finite limitations, greatly seeking after knowledge and certainty, and finding the very curiosity of their discontent the weapon of their own destruction. The theme is an eternal one in tragedy, but it was left to the romanticists fully to realize its meaning, and to Byron to give it isolation and grandeur.