The republic by Plato is a book about questioning what is Justice, but it is also about how to find the True Form of the Good. Actually at the end of book IX, Socrates surprisingly says that the construction of the Just City can probably never happen on this earth and that we must construct it within our minds instead. But how do go about that? One hint is given in The Symposium, by the Priestess from Mantinea, Diotima.
She says, and I am quoting from the end of the Republic by Plato, Appendix I, translated by Desmond Lee, by Penguine books (Because he summarizes it so well. I paraphrase it here with additions):
Anyone who wants to pursue this goal correctly must begin by turning to physical beauty, and then if he (or she) gets the right guidance fall in love with a particular individual and with her (or him) produce thought of beauty. He/She must then perceive that the beauty in one individual is similar to that in another, and that if beauty of form is what he/she is pursuing it is stupid not to recognize that the beauty exhibited by all individuals is the same. With that recognition he/she becomes the lover of all physical beauty, and his/her passion for a single individual slackens as something of a small account.
The next stage is for him/her to reckon beauty of mind more valuable than beauty of body, and if he/she meets someone who has an attractive mind but little bodily charm, to be content to love and care for him/her and produce thoughts which improve the young; this again will compel him/her to look for beauty in habits of life and customs and to recognize that here again all beauty is akin, and that bodily beauty is a poor thing in comparison.
From ways of life he/she must proceed to forms of knowledge and see their beauty too, and look to the fullness of beauty as a whole, giving up the slavish and small-minded devotion to individual examples, whether a girl or boy, man or woman, or a way of life, and turning instead to the great sea of beauty now before their eyes. They can then in their generous philosophical love beget great and beautiful words and thoughts, and be strengthened to glimpse the one supreme form of knowledge, whose object is the beauty of which I will now speak…For anyone who has been guided so far in their pursuit of love, and surveyed these beauties in right and due order, will at this final stage of love suddenly have revealed to himself or herself a beauty whose nature is marvelous indeed, which is the culmination of all his/her efforts.
Plato, The Symposium, Lines 210a-e
Another is that we must meditate and look inwards. This is suggested by Buddhism, but also by Stoicism. Marcus Aurelius says that we should not expect or hope for Plato’s Republic. We should not even hope for approval by others. This is a personal journey.
Marcus Aurelius says:
The universal cause is a torrent, sweeping everything in its stream. So, man, what does that mean for you? Do what nature requires at this moment. Start straight away, if that is in your power: don’t look over your shoulder to see if people will know. Don’t hope for Plato’s utopian republic, but be content with the smallest step forward, and regard even that result as unimportant.
μὴ τὴν Πλάτωνος πολιτείαν ἔλπιζε.
Marcus Aurelius, Meditations, Book IX, 29.
Bronson Alcott, and George Ripley, tried to found Utopian Schools in Massachusetts in the 19th century, but these schools, Fruitlands and Brookfarm, failed miserably. Bronson Alcott’s daughter, yes, you know her, Louis May Alcott, wrote about it in Wild Oats. So find beauty in things and knowledge. Find it in architecture, nature, in your own mind. Find it in the minds of others, not just their bodies.
Menander sums it up in one of his Sententiae #851:
Ψυχῆς ὄλεθρός ἐστι σωμάτων ἔρως.
Destruction of/for the soul is love of bodies (only).
I added the implicit, “only”. So although we all start out loving bodies and people, you must progress beyond this to attain true knowledge and wisdom, and to see the Form of the Good.