The partnership brought vast territories controlled by the Grand Duchy of Lithuania into Poland's sphere of influence and proved beneficial for both the Polish and Lithuanian people, who coexisted and cooperated in one of the largest political entities in Europe for the next four centuries.

Polish towns, lacking national representation protecting their class interests, preserved some degree of self-government (city councils and jury courts), and the trades were able to organize and form guilds.

In 1415, Paulus Vladimiri, rector of the Kraków Academy, presented his Treatise on the Power of the Pope and the Emperor in respect to Infidels at the council, in which he advocated tolerance, criticized the violent conversion methods of the Teutonic Knights, and postulated that pagans have the right to peaceful coexistence with Christians and political independence.

This dependence on nobility-controlled agriculture in central-eastern Europe diverged from the western part of the continent, where elements of capitalism and industrialization were developing to a much greater extent, with the attendant growth of a bourgeoisie class and its political influence.

[26] Most of the exported grain left Poland through Gdańsk (Danzig), which became the wealthiest, most highly developed, and most autonomous of the Polish cities because of its location at the mouth of the Vistula River and access to the Baltic Sea.

[26][27] During the 16th century, prosperous patrician families of merchants, bankers, or industrial investors, many of German origin, still conducted large-scale business operations in Europe or lent money to Polish noble interests, including the royal court.

Jealous of their class privilege ("freedoms"), the Renaissance szlachta developed a sense of public service duties, educated their youth, took keen interest in current trends and affairs and traveled widely.

[32] The notable Sandomierz Agreement of 1570, an act of compromise and cooperation among several Polish Protestant denominations, excluded the Arians, whose more moderate, larger faction toward the end of the century gained the upper hand within the movement.

While the pioneering Polish humanists, greatly influenced by Erasmus of Rotterdam, accomplished the preliminary assimilation of the antiquity culture, the generation that followed was able to put greater emphasis on the development of native elements, and because of its social diversity, advanced the process of national integration.

The Reformation resulted in the establishment of a number of gymnasiums, academically oriented secondary schools, some of international renown, as the Protestant denominations wanted to attract supporters by offering high quality education.

Copernicus' De revolutionibus orbium coelestium, published in Nuremberg in 1543, shook up the traditional value system extended into an understanding of the physical universe, doing away with its Christianity-adopted Ptolemaic anthropocentric model and setting free the explosion of scientific inquiry.

Copernicus wrote Latin poetry, developed an economic theory, functioned as a cleric-administrator, political activist in Prussian sejmiks, and led the defense of Olsztyn against the forces of Albrecht Hohenzollern.

Maciej Miechowita, a rector at the Cracow Academy, published in 1517 Tractatus de duabus Sarmatiis, a treatise on the geography of the East, an area in which Polish investigators provided first-hand expertise for the rest of Europe.

[36] Bishop Wawrzyniec Goślicki (Goslicius), who wrote and published in 1568 a study entitled De optimo senatore (The Counsellor in the 1598 English translation), was another popular and influential in the West political thinker.

At that time the Polish language, common to all educated groups, matured and penetrated all areas of public life, including municipal institutions, the legal code, the Church, and other official uses, coexisting for a while with Latin.

Among Kochanowski's best known works are bucolic Frascas (trifles), epic poetry, religious lyrics, drama-tragedy The Dismissal of the Greek Envoys, and the most highly regarded Threnodies or laments, written after the death of his young daughter.

Polish magnates, Silesian Piast princes in Brzeg, and even Kraków merchants (by the mid 16th century their class economically gained strength nationwide) built or rebuilt their residencies to make them resemble the Wawel Castle.

[42] During the reign of Sigismund I, szlachta in the lower chamber of general sejm (from 1493 a bicameral legislative body), initially decidedly outnumbered by their more privileged colleagues from the senate (which is what the appointed for life prelates and barons of the royal council were being called now),[43] acquired a more numerous and fully elected representation.

The legal pronouncements, intended to facilitate the functioning of a uniform and centralized state, with ordinary szlachta privileges strongly protected, were frequently ignored by the kings, beginning with Sigismund I, and the upper nobility or church interests.

Bona's sway over the king and the magnates, her efforts to strengthen the monarch's political position, financial situation, and especially the measures she took to advance her personal and dynastic interests, including the forced royal election of the minor Sigismund Augustus in 1529 and his premature coronation in 1530, increased the discontent among szlachta activists.

Among the movement's demands were termination of the kings' practice of alienation of royal domain, giving or selling land estates to great lords at the monarch' discretion, and a ban on concurrent holding of multiple state offices by the same person, both legislated initially in 1504.

[44] Despite the favorable economic development, the military potential of 16th century Poland was modest in relation to the challenges and threats coming from several directions, which included the Ottoman Empire, the Teutonic state, the Habsburgs, and Muscovy.

In 1569 Royal Prussia had its legal autonomy largely taken away, and in 1570 Poland's supremacy over Danzig and the Polish King's authority over the Baltic shipping trade were regulated and received statutory recognition (Karnkowski's Statutes).

[51] In 1515, during a congress in Vienna, a dynastic succession arrangement was agreed to between Maximilian I, Holy Roman Emperor and the Jagiellon brothers, Vladislas II of Bohemia and Hungary and Sigismund I of Poland and Lithuania.

Grand Master Wilhelm von Fürstenberg accepted the Polish–Lithuanian conditions without a fight, and according to the 1557 Treaty of Pozvol, a military alliance obliged the Livonian state to support Lithuania against Moscow.

[56] Sigismund II's childlessness added urgency to the idea of turning the personal union between Poland and the Grand Duchy of Lithuania into a more permanent and tighter relationship; it was also a priority for the execution movement.

Lithuania's laws were codified and reforms enacted in 1529, 1557, 1565–1566 and 1588, gradually making its social, legal and economic system similar to that of Poland, with the expanding role of the middle and lower nobility.

[60] By the Union of Lublin a unified Polish–Lithuanian Commonwealth (Rzeczpospolita) was created, stretching from the Baltic Sea and the Carpathian mountains to present-day Belarus and western and central Ukraine (which earlier had been Kievan Rus' principalities).

Moreover, the nobility's uppermost stratum was about to assume the dominant role in the Commonwealth, as magnate factions were acquiring the ability to manipulate and control the rest of szlachta to their clique's private advantage.

[69][70] In Poland–Lithuania the Jews were increasingly finding employment as managers and intermediaries, facilitating the functioning of and collecting revenue in huge magnate-owned land estates, especially in the eastern borderlands, developing into an indispensable mercantile and administrative class.