Rabba once created a man (out of dust) and sent him to Rabbi Zira, who
having addressed the figure and received no answer, said, "Thou art
(made) by witchcraft; return to thy native dust." Rav Chaneanah and Rav
Oshayah sat together every Sabbath-eve studying the book Yetzirah (i.e.,
the book of Creation), until they were able to create for themselves a
calf (as large as a) three-year old, and they did eat thereof.
THE TALMUD, _Sanhedrin_, fol. 65, col, 2.