The Jewish communities of Eastern Europe in the late 17th and early 18th Centuries were devastated. From 1648 - 1654, "the greatest Jewish suffering since the Crusades [Porath, 33]" occurred which have been misleadingly coined the Ukrainian uprisings. This period, in Hebrew, is known as the Tach v"Tacht (the phrase represents all eight of the years, but is actually an acronym for the two worst years, the beginning years of the uprisings, 1648-49). Cossack anti-Semite Bogdan Chmelnicki led his fellow Cossacks, who were also Ukrainian peasants, throughout Europe to slaughter Jews. Historians say that anywhere from 100,000 to 125,000 Jews were slain: twenty to twenty-five percent of the Jewish population of Europe at that time [http://www.webinfonet.net/heritage/history.html, 10/29/01]. .
Many leaders attempted to arise from the occasion as Jewish leaders, but none of the flames could endure; no one could truly captivate the people enough to make his/her movement credible in the mind of the public. Then, in the early 18th Century, enters Israel Ben Eliezer, the man known as the Ba"al Shem Tov, Israel Ba"al Shem Tov, or Besht, the founder of Hasidism. He truly captivated the public as a strong, able leader whose philosophies were consistent with that of the working class, anti-intellectual, faithless Jew. Therefore, the entrance of Hasidism into the lives of Polish Jews, and eventually Jews around the world was a result of the need for blind faith in hard times, dissatisfaction with options available, and previously unseen able leadership.
In order to truly understand Hasidism, we must attempt to understand the man to whom "more legends have been woven around than around Moses, father of the Prophets [Rabinowicz, 29]" : Israel Ba"al Shem Tov, and his theological philosophies. Israel Ba"al Shem Tov (abbreviated as Besht) was born circa 1700 as part of a poor Polish family. He was an orphan at a young age, and was sent by benevolent neighbors to a heder, a Jewish day school in which Talmud, the book of commentaries and interpretations of Torah, is studied.
