"You shall love your fellow as yourself" (Leviticus 19:18). Hillel the Elder called this the entire Torah, with everything else being commentary. Chapter thirty-two of the Tanya explains how to actually do it.
The key, says Rabbi Schneur Zalman, is which part of the other person you are looking at. If you focus on bodies—his body versus your body, his interests versus yours, his status versus yours—love is impossible. Bodies are separate. They compete for the same resources. Every gain for him is a potential loss for you.
But if you focus on souls, the picture reverses. All Jewish souls share a single root in the one God. They are, in the Tanya's language, "all of a kind, and all having one Father." Siblings from the same parent. The more weight you give to the soul and the less weight you give to the body, the more natural it becomes to love the other person—because at the soul level, there is no "other." You are one.
This is why people who prioritize their physical existence cannot sustain genuine love. Their love is "dependent on a thing" (Avot 5:16)—conditional, transactional, subject to change when circumstances shift. But love rooted in the shared divine source of all souls is unconditional, because the source never changes.
The Tanya addresses an obvious objection: what about people who sin? Aren't we supposed to hate the wicked? Yes—but only under specific conditions. The obligation to hate applies only to someone who is your "companion in Torah and commandments," whom you have personally rebuked, and who has refused to change. For everyone else, Hillel's instruction applies: "Be of the students of Aaron, loving peace and pursuing peace, loving people and drawing them near to Torah." Even total strangers. Even people who seem far from observance. The Tanya says you should draw them close with bonds of love—and perhaps the light of your love will inspire their return.
At the cosmic level, this love is not just an ethical imperative. It is a structural necessity. God's light can only rest in a unified vessel. Disunity among souls creates cracks that the Shechinah cannot inhabit. The prayer says: "Bless us, our Father, all of us as one." Only as one.
Acting on the suggestion mentioned above—to view one’s body with scorn and contempt and finding joy only in the joy of the soul alone—is a direct and easy way to attain the fulfillment of the commandment “You shall love your fellow as yourself”1 Leviticus 19:18. toward every soul of Israel, both great and small. For, whereas one despises and loathes one’s body, while as for the soul and spirit, who can know their greatness and excellence in their root and source in the living G–d? Being, moreover, all of a kind and all having one Father—therefore, all Israelites are called real brothers by virtue of the source of their souls in the One G–d; only the bodies are separated. Hence in the case of those who give major consideration to their bodies while regarding their souls as of secondary importance, there can be no true love and brotherhood among them, but only [a love] which is dependent on a [transitory] thing.2 Avot 5:16. This is what Hillel the Elder meant when he said in regard to the fulfillment of this commandment, “This is the whole Torah, while the rest is but commentary,”3 Shabbat 31a. and so on. For the basis and root of the entire Torah are to raise and exalt the soul high above the body, reaching to the Source and Root of all the worlds, and also to bring down the Light of the En Sof, blessed is He, upon the community of Israel, as will be explained later,4 Ch. 41. i.e., into the fountainhead of the souls of all Israel, to become “One into One.”5 Zohar II:135a. This is impossible if there is, G–d forbid, disunity among the souls, for the Holy One, blessed is He, does not dwell in an imperfect place,6 Zohar I:216b. as we pray, “Bless us, our Father, all of us as one, with the light of Your Countenance,”7 Liturgy, Amidah. as has been explained at great length elsewhere. As for the Talmudic statement8 Shevuot 30a. to the effect that one who sees his friend sinning should hate him and should tell his teacher to hate him also, this applies to a companion in Torah and precepts, having already applied to him the injunction, “You shall repeatedly rebuke your friend (amitecha),”9 Leviticus 19:17. meaning “He who is with you in Torah and precepts,”10 A play on the word עמיתך: עם-אתך. See Kitzurim V’Hearot, p. 36. and who, nevertheless, has not repented of his sin, as stated in Sefer Charedim.11 By Rabbi Eliezer Azkari (16th century). But as for the person who is not one’s colleague and is not on intimate terms with him, Hillel the Elder said, “Be of the disciples of Aaron, loving peace and pursuing peace, loving the creatures and drawing them near to the Torah.”12 Avot 1:12. This means that even in the case of those who are removed from G–d’s Torah and His service and are therefore classified simply as “creatures,” one must attract them with strong cords of love, perchance one might succeed in drawing them near to the Torah and Divine service. Even if one fails, one has not forfeited the merit of the precept of neighborly love. Even with regard to those who are close to him, and whom he has rebuked, yet they had not repented of their sins, when he is enjoined to hate them, there still remains the duty to love them also, and both are right: hatred because of the wickedness in them, and love on account of the aspect of the hidden good in them, which is the Divine spark in them, which animates their divine soul. He should also awaken pity in his heart for [the divine soul], for she is held captive, as it were, in the evil of the sitra achara that triumphs over her in wicked people. Compassion destroys hatred and awakens love, as is known from the [interpretation of the] text, “To [the house of] Jacob who redeemed Abraham.”13 Isaiah 29:22. See Torah Or 51a-b. [As for King David, peace unto him, who said, “I hate them with a consummate hatred,”14 Psalms 139:22. he was referring to [Jewish] heretics and atheists who have no portion in the G–d of Israel, as stated in the Talmud, Tractate Shabbat, beginning of ch. 16.]
