Ger. Mann ist was Mann isst, man is what man eats; cf. the philosopher Ludwig Feuerbach (1804-72) in Jacob Moleschott Lehre der Nahrungsmittel: Für das Volk (1850) ‘Advertisement’: Der Mensch ist, was er isst, Man is what he eats. The saying is sometimes attributed to the French gastronome Anthelme Brillat-Savarin who wrote in his Physiologie du Goût (1825): Dis-moi ce que tu manges, je te dirai ce que tu es, Tell me what you eat, and I will tell you what you are.The Torah prescribes a strict diet for the Jewish People. According to the "The Path of the Just", we are dealing with a spiritual version of "you are what you eat":
The sin which comes third after theft and illicit relations in respect to desire is that of forbidden foods - whether thos; that are ritually unclean, or an admixture containing them, or a combination of meat and milk, or suet, or blood, or food cooked by gentiles, or the utensils of gentiles, or the wine used in ther libations, or their drinking-wine. Cleanliness in relation to all of these requires great scrutiny and self-strengthening because there is a lust in the heart for good foods and because one must sometimes suffer a monetary loss as a result of admixtures and the like. The prohibitions concerning forbidden foods also involve many details, as is reflected in all of the commonly known laws that are treated in the Halachic writings. One who is lenient in relation to these laws when he has been instructed to be stringent is destroying his soul. As is stated in the Sifra (Shemini), " `Do not sully yourselves with them, becoming unclean with them' (Leviticus 11:43) - if you sully yourselves with them, you will, in the end, partake of their uncleanliness." Forbidden foods carry uncleanliness itself into a person's heart and soul until the holiness of the Presence Blessed be He departs and withdraws from him, as is also stated in the Talmud ( Yoma 39a), " `...becoming unclean with them' - do not read `becoming unclean with them,' but `becoming dull with them.' " For sin dulls a man's heart in that it causes to depart from him true knowledge and the spirit of wisdom that the Holy One Blessed be He gives to the Saints (as it is said [Proverbs 2:6], "For God gives wisdom"), and he remains beastly and earthy, immersed in the grossness of this world. Forbidden foods are worse in this respect than all other prohibitions, for they enter into a person's body and become flesh of his flesh. In order to instruct us that this applies not only to unclean beasts or to earth creatures, but also to those animals, which, though in the "clean" category, are ritually unclean, Scripture tells us (Leviticus 11:47), "To distinguish between the unclean and the clean," upon which our Teachers of blessed memory comment (Sifra ad loc.), "There is no need to point up the distinction between an ass and a cow. What, then, is the meaning of `between the unclean and the clean'? - between what is unclean to you and what is clean to you; between the cutting of most of the windpipe and the cutting of half. And what is the difference between most and half ? - a hairs-breadth." The reason that they concluded in this manner ("And what is the difference between `most' ... ") is to show how amazing the power of the mitzvoth is, that a hair's-breadth constitutes the difference between uncleanliness and cleanliness itself.I claim that "you are what you see, what you hear, and what you read". Whatever your mind is dealing with, that is "you" at that very moment. This is perhaps one of the reasons that our sages said, "Thoughts of sin are worse than the sin itself (Yoma 29A)". The sin itself may be performed by one's hands, mouth, or whatever. This is a serious matter in and of itself which requires teshuvah. However, "thoughts of sin" go much deeper, entering the intimate recesses of one's inner being.
Anyone possessed of sense will regard forbidden food as poison, or as food with which some poison has become mixed. Would anyone allow himself to partake of such food? If there were any room for suspicion or even the slightest doubt, he would certainly not permit himself to eat of it; and if he did, he would be regarded as an absolute fool. Forbidden food, as we have explained, is poison itself to the heart and soul."
This is why it is so important to be close to Torah scholars, to invest time in learning Torah. Then one's mind is occupied with positive things: mitzvot, ethics, midot, holiness (Leviticus 19:1-2):
1 And the LORD spoke unto Moses, saying: 2 Speak unto all the congregation of the children of Israel, and say unto them: Ye shall be holy; for I the LORD your God am holy.Of course, the opposite is also true: If one hangs around with fools, scoffers, and/or slanderers, takes part in their conversations, and reads their books (or blogs), one fills his mind with filth and vulgarity. That is what his mind is occupied with, and to a certain degree that is "him" at that very moment. Holiness and impurity cannot dwell together.
God has clearly put two paths before us. We shall chose holiness and life.