“To know and love one other human being is the root of all wisdom.”

Majlisi, Bihārul Anwār, vol.78, p. 164

Twitter 6 Mar 2017
2017

Variant: The only thing that we know is that we know nothing — and that is the highest flight of human wisdom.
Source: War and Peace (1865–1867; 1869), Ch. I

Letter Seven (14 May 1904)
Letters to a Young Poet (1934)
Variant: For one human being to love another human being: that is perhaps the most difficult task that has been given to us, the ultimate, the final problem and proof, the work for which all other work is merely preparation.
Source: The Selected Poetry of Rainer Maria Rilke
Context: People have (with the help of conventions) oriented all their solutions toward the easy and toward the easiest side of the easy; but it is clear that we must hold to what is difficult; everything alive holds to it, everything in Nature grows and defends itself in its own way and is characteristically and spontaneously itself, seeks at all costs to be so and against all opposition. We know little, but that we must hold to what is difficult is a certainty that will not forsake us; it is good to be solitary, for solitude is difficult; that something is difficult must be a reason the more for us to do it.
To love is good, too: love being difficult. For one human being to love another: that is perhaps the most difficult of all our tasks, the ultimate, the last test and proof, the work for which all other work is but preparation.

Introduction to "National Brotherhood Week"
That Was the Year That Was (1965)

25 Things Even My Best Friends Didn’t Know Until Now (1 October 2009).
Context: In a day, sometimes I feel so much love for the world, I think my heart is bursting. Sometimes, I feel so scared, I want to shrink myself even further. I think that’s what happened to us gods and goddesses. Like the dinosaurs, we realized that it’s too dangerous to be so large. So we kept shrinking ourselves to what we are now. We might get even smaller. I see the sign in the engineers making smaller gadgets, smaller and smaller. Pretty soon, our fingers will be too large to operate them. So what are we doing? I trust in the human wisdom. We are incredibly intelligent beings. So we might know something without thinking that we know…. Well, even my best friend didn’t know until now that I was thinking of crazy things like this.

Book 1 (Sefer HaMadda'<!--[sic]-->), 4.12
Mishneh Torah (c. 1180)
Context: When a man reflects on these things, studies all these created beings, from the angels and spheres down to human beings and so on, and realizes the divine wisdom manifested in them all, his love for God will increase, his soul will thirst, his very flesh will yearn to love God. He will be filled with fear and trembling, as he becomes conscious of his lowly condition, poverty, and insignificance, and compares himself with any of the great and holy bodies; still more when he compares himself with any one of the pure forms that are incorporeal and have never had association with any corporeal substance. He will then realize that he is a vessel full of shame, dishonor, and reproach, empty and deficient.