Frederick William had recourse to the arts of diplomacy and dissimulation of which he was so consummate a master. In 1663 the diet accepted at his hands a charter which defined its rights. It was expressed in ample but vague phraseology. By it the Great Elector agreed that his own powers of government should be only those formerly enjoyed by himself and the king of Poland, that the diet should be summoned at least once in six years, and should be consulted in all important business, and that no new taxes should be imposed without its consent. But by the very definition of its powers the diet lost all which was not expressed, while the elector gained all that was not refused. The balance of authority in the state had clearly shifted from the diet to the elector. Frederick William had only to avoid for a few years giving the diet the opportunity of exercising the rights secured to it, while the authority of his own administrative officers was being established, and he need no longer fear the diet when it did meet, than the kings of France need fear the States-General. It might be troublesome but it could not be dangerous. So gradually by thrifty management and careful policy Frederick William succeeded in extending his personal authority more and more over the country, until in 1672 he felt himself strong enough to strike a final blow. Kalkstein, the head and front of the opposition to him, had been banished to his estates for treasonable correspondence with Poland in 1669, but breaking his parole he escaped across the frontier to Warsaw. Frederick William demanded his surrender from the king of Poland, but it was refused. [Sidenote: =Execution of Kalkstein.=]Taking the law into his own hands, he had him arrested on Polish ground, brought to Memel, and there beheaded. A more flagrant breach of the rights of nations could not have been conceived, but the Great Elector well knew it could not fail to be successful, and with him success justified everything. Poland was in no condition to declare war, and the death of Kalkstein was the one thing wanted to make the submission of Prussia complete. [Sidenote: =Establishment of personal government by the Great Elector.=]