But this dangerous division between the thinking and the fighting forces of the Utraquist party was checked by two events which were both of considerable importance in the history of the movement. The first of these was the death of Nicholaus of Hus, who was thrown from his horse as he was leaving Prague. This death naturally threw more power into the hands of Z̆iz̆ka; and he had always felt, much more strongly than Nicholaus, the necessity of maintaining the alliance with the Calixtine rulers of Prague. The other event, which drew the more moderate men of the two parties together, was the outbreak of a new division in the ranks of the Taborites themselves. That a body, with the origin, constitution, and mode of life which have been already described, should develop new and unexpected phases of thought, might have been guessed from the beginning of the movement; but that the particular doctrine now broached should have caused division among any section of the Utraquists must sound very strange to modern ears. In any revolt against excessive priestly power, one would have expected that such a doctrine as Transubstantiation would have been the first to be attacked. Yet, while both Calixtines and Taborites were fiercely denouncing the civil power of the clergy, while they were attacking every outward badge which seemed to separate the clergy from the laity, they had yet shrunk with horror from any attack on the doctrine of Transubstantiation. When, then, Martinek Hauska, a leading Taborite preacher, began to denounce this doctrine, he roused the fiercest opposition among his Taborite colleagues; and two of their more learned members wrote, in February, 1421, to Jakaubek of Kladrau and John Pr̆zibram, to consult them about the best means for opposing this heresy. The answer to that question was only too easily given; for, while each party disagreed with every other on the definition of heresy, there was a striking unanimity about the right method of dealing with it when defined. So, while the Calixtines burnt one of the preachers of the new doctrine in Prague, the Taborites, doubtless finding them too numerous for such treatment, forcibly expelled them from Tabor.