Epictetus, a stoic roman philosopher who was once a slave, has a matter-of-fact, no nonsense way of speaking. In a sense he picks up where Aristotle left off, thinking of love as the end of a philosophical, intellectual pursuit, something to converse about and figure out. To love well is to know what is good, for you and everyone:
“Whoever, then understands what is good, can also know how to love; but he who cannot distinguish good from bad, how can he possess the power of loving? To love, then is only in the power of the wise.”
The foolish person, for example, does not understand that wealth and power are actually not good for you, and therefore he should not love them. Good things are always internal things and always within your power to get. What gets in the way of people loving well is self interest, or selfishness, especially misdirected self interest: “Every animal is attached to nothing so much as to its own interest,” he warns us, and the key to loving well is to “put in the same place his interest, sanctity, goodness, and country, and parents, and friends.” In other words, try not to put your interests above others, and then "all of these will be secured:”
“If then I am there where my will is, then only shall I be a friend such as I ought to be, and son, and father; for this will be my interest, to maintain the character.”
So when looking for friends, only notice whether they love external or internal things (the "will"). If the latter, “confidently declare that they are friends, as you declare that they are faithful, that they are just.” Why is the “will” so important for Stoicism? Because it is the thing that thinks, and chooses to act, and believes; it is “us.”
And now for the part of Stoicism that people remember it for...He is against the romantic sensationalist love of Romeo and Juliet. People who weep at loved ones leaving or dying or because they are dependant on them is silly and not reasonable and out of our control. People will leave, and die. It is not reasonable to “depend on another.” “And what prevents you from loving another as a person subject to mortality, as one who may go away from you?” Treat those you love as “a bunch of grapes at the appointed season…if you wish for these things in winter, you are a fool… “such is every event which happens from the universe to the things which are taken away according to its nature.” Here is the unshakable Stoic Will not crying at a funeral because....hey, people die man.
Here is an elaboration of Aristotle’s idea that we should love our self (parallels to Ayn Rand?):
“This is not a perverse self-regard, for the animal is constituted so as to do all things for itself. For even the sun does all things for itself; nay, even Zeus himself…and universally, he has made the nature of the rational animal such that it cannot obtain any one of its own proper interests, if it does not contribute something to the common interest.” In other words, doing the right thing for yourself is doing good for everyone.
For love of humanity, Epictetus draws on the idea that we are all brothers and citizens because we all come from God:
“He then who has observed with intelligence the administration of the world, and has learned that the greatest and supreme and the most comprehensive community is that which is composed of men and God, and that from God have descended the seeds not only to my father and grandfather, but to all beings…why should not such a man call himself a citizen of the world, why not a son of God, and why should he be afraid of anything which happens among men? Is kinship with Caesar…sufficient to enable us to live in safety?”
There is another main tenant of Stoicism. Other than only worrying about that things that are in your power, there is the tenant that you should not worry about the things that are not in your power. In other words, never worry. The key to “tranquility of mind,” and “freedom” and “magnanimity” is trusting, or showing "affection" for, God:
“Lift up your head at last as released from slavery. Dare to look up to God and say, “Deal with me for the future as thou wilt; I am of the same mind as thou art; I am thine: I refuse nothing that pleases thee: lead me where thou wilt: clothe me in any dress thou choosest.” … “sadness, fear, desire, envy, malevolence, avarice, effeminacy, intemperance. But it is not possible to eject these things otherwise than by looking to God only, by fixing your affections on him only, by being consecrated to his commands. But if you choose anything else, you will with sighs and groans be compelled to follow what is stronger than yourself, always seeking tranquility and never able to find it; for you seek tranquility there where it is not, and you neglect to seek it where it is.”
Discourses of Epictetus