In the last decades of the eighteenth century, Hasidism spread with incredible rapidity among the Jewish masses of Poland and partly even of Lithuania. Numerous communities saw the rise of Hasidic congregations and the establishment of separate houses of prayer, in which services, characterized by boundless ecstasy, violent shouts, and gestures, were held in accordance with Besht's prescriptions. The Hasidim adopted the Cabalistic prayer-book of Ari, which differed from the accepted liturgy by numerous textual alterations and transpositions. They neglected the traditional time limit for morning prayers, changed the ritual of slaughtering animals, and some of them were in the habit of dressing themselves in white on the Sabbath. They were fond of whiling away their time in noisy assemblies, and frequently indulged in merry drinking bouts, to foster, in accordance with Besht's precept, "a cheerful disposition."
The most characteristic trait of the Hasidim, however, was their boundless veneration of the "holy" Tzaddiks. Though logically the outcome of Hasidism, in practice Tzaddikism was in many cases its forerunner. The appearance of some miracle-working Tzaddik in a certain neighborhood frequently resulted in wholesale conversions to Hasidism. The Tzaddik's home was overrun by crowds of men and women who in their credulity hoped to obtain a cure for diseases or a remedy for the sterility of their women, or who asked for a blessing, for predictions of the future, or sought advice in practical matters. If, in one case out of many, the Tzaddik succeeded in helping one of his clients, or if one of his guesses or predictions proved to be correct, his fame as a miracle-worker was firmly established, and the population of the neighborhood was sure to be won over to Hasidism.
The number of Hasidic partisans grew in proportion to the number of Tzaddiks, of whom there were a great many in the last two decades of the eighteenth century. The most authoritative Tzaddiks came from the circle of Baer of Mezherich. Every one of them either laid his own individual impress upon the doctrine preached by him, or endeavored to adapt himself to the habits of the population of his district. As a result, the Hasidic doctrine branched out rapidly, falling into different varieties. The principal branches of Hasidism were two: that of Poland and Ukraina, and that of Lithuania and White Russia.