The Torah in Parashat Shoftim (Debarim 18:10) commands that there may not be a “Kosem Kesamim” among Beneh Yisrael. This refers to somebody who connects to various spiritual forces through which he can predict the future. This was done in ancient times by isolating oneself and focusing on certain things which enabled one to see future events. The Rambam, in Sefer Ha’misvot, writes that he saw these kinds of “Kosemim,” sorcerers who foretold the future. Some would throw a belt onto the ground and then make predictions based on the shape the belt formed when it landed. Others would place stones in bags, throw the bags on the ground, and then make predictions based on the arrangement of the stones inside the bag. There were also those would hit a stick on the ground and focus on it in order to see future events. (These forms of sorcery enabled people to predict the near future; only true prophets were empowered to foresee events in the distant future.) All these practices are strictly forbidden.
The Sefer Ha’hinuch explains that the Torah forbade these practices because they can have the effect of undermining a person’s Emuna (faith in Hashem). One who accustoms himself to these practices will likely start believing that the spiritual forces are independently powerful, beyond the control of G-d, Heaven forbid. We are to believe that “En Od Mi’lebado” – there is absolutely no force or power in existence that restrains G-d in any way; He exerts absolute, unlimited control over everything in the universe, and there is nothing that can limit or restrain Him. We also believe that “En Mazal Le’Yisrael” – the Jewish Nation is not subject to any sort of mystical force, and we are controlled exclusively and directly by Hashem. If a person utilizes means of foreseeing the future, he will assume that the predicted outcome is certain to occur, without believing that G-d can bring a different outcome. In order for us to retain our firm Emuna, the Torah forbade us from predicting the future through sorcery.
This prohibition applies in all places and at all times, and is binding upon both men and women. One who performs an action to determine the future transgresses this command and is liable to Malkut.
The Sefer Ha’hinuch writes that the Torah here forbids performing these acts. Consulting with a sorcerer about future events is not included under this prohibition, though, in the Sefer Ha’hinuch’s words, doing so is “Meguneh Me’od” – especially repulsive.
The Sefer Ha’hinuch adds in this context an analysis of the word “Yisrael” by which our nation is known. This name, of course, was given to Yaakob, the third of the three patriarchs, and it is thus commonly assumed that we are called “Yisrael” because we descend from Yaakob who received this name. However, the Sefer Ha’hinuch posits that in truth, even Abraham and Yishak bore this name. The verse in the Book of Shemot (12:40) tells that Beneh Yisrael resided in Egypt for 430 years – despite the fact that G-d had informed Abraham that his descendants would spend just 400 years in a foreign land (Bereshit 15:13). The commentators explain that the 400-year period began with the birth of Yishak, and the extra thirty years are the interim years between the time Abraham received this prophecy, and Yishak’s birth. It thus emerges, the Sefer Ha’hinuch observes, that during the first thirty of the 430 years which Beneh Yisrael are said to have spent under foreign rule, only Abraham Abinu was affected. The fact that the Torah says that “Beneh Yisrael” spent 430 years in exile thus proves that Abraham himself was called “Yisrael.”
As for Yishak Abinu, the Sefer Ha’hinuch cites the opening verse of the Book of Shemot – “These are the names of the children of Israel who came to Egypt.” The first person named after this introduction is Yaakob, proving that Yaakob is included in “the children of Israel.” Necessarily, then, Yishak – Yaakob’s father – is also referred to as “Yisrael.”
The reason, the Sefer Ha’hinuch writes, is that the word “Yisrael” means “Sar El,” which refers to dominion over the angelic forces in the heavens. All three of the patriarchs – and their offspring, for all time – transcend these forces, and are not under their control. We are called “Yisrael” precisely for this reason – because we exert control over the “Sarim,” the angels in heaven, through our Misvot. The Sefer Ha’hinuch gives several examples of great Sadikim who overturned the laws of nature, such as when Yehoshua made the sun stop in the sky to lengthen the day. This and other similar instances demonstrate the concept of “Yisrael,” the unique power that we all have as descendants of Abraham, Yishak and Yaakob.
The Sefer Ha’hinuch explains that this is why sorcery and witchcraft are considered such grievous offenses. One who seeks to access these forces essentially denies the belief in the special power of Am Yisrael, our ability to subdue these forces through our good deeds.