this political system unusual for its time stemmed from the ascendance of the szlachta noble class over other social classes and over the political system of monarchy. in time, the szlachta accumulated enough privileges (such as those established by the nihil novi act of 1505) that no monarch could hope to break the szlachta's grip on power. the commonwealth's political system is difficult to fit into a simple category, but it can be tentatively described as a mixture of: