The Kingdom of Poland, in a federal union with the Grand Duchy of Lithuania, became, in the 15th and 16th centuries, an important power in Central Europe. The Polish civilization took the side of the West but still remained open to another Europe. The Commonwealth—in the English of the day—was a constitutional and parliamentary alternative to Western absolutism and Eastern despotism. The multi-ethnic and multi-religious identity of the Commonwealth was ensured by law. This pax Jagellonica had latent weaknesses in politics, both internal and external.