"Be Kind" -- Says Who?

This past week, one of my students turned in an opinion paper that had what I felt was a very thought provoking quotation: "Be kind, for everyone you meet is fighting a hard battle." The student attributed this saying to Plato in her paper, and in fact, I ran a Google search for the quotation along with the name Plato and found other references to it. I noted, however, that none of the attributions of the saying also included the source.

The more I thought about this quotation, the more I liked it. It communicates the need for empathy. It is in keeping with Jesus' so-called "golden rule" (“Treat others in the same way that you would want them to treat you” [Luke 6:31 NET]), which is the overriding ethic I seek to live by.

I liked the saying so much, I added it to the top of my blog, and it may still be there if you are reading this in the week I am writing it.

Then today, I got an email from a person who had found my site through Google. She corrected the saying I had at the top of my blog, suggesting instead that it came from
Philo. So I ran a Google search with the saying, plus the name Philo, and sure enough, I found the quotation attributed to Philo as well. Again, however, no source was mentioned.

So remembering that I had the works of Philo in
Accordance in both Greek and English, I ran a search simply for "Be kind" in the English module. No such luck. Then I ran the same search through every Accordance module I own--multitudes of reference works, hundreds of journals, extra-biblical texts such as the Pseudepigrapha, apocryphal Gospels, Jewish writings, the Church Fathers--easily over a million pages, I would guess.

[Unrelated to this quotation, I found another interesting saying from Pseudo-Chrysostom, quoted by Aquinas: "If God be kind, should His Priest be harsh?"]

Still no definitive source, but now the situation got murkier. One particular Accordance module,
The Complete Gathered Gold (a collection of quotations) attributes the saying to two other individuals: Ian MacLaren and Harry Thompson! I'm not sure who either of these individuals are. No source was listed for either attribution.

So, it's a mystery at this point. Does anyone know the actual source for this saying? If you do, please leave the answer in the comments so that I can correct the heading at the top of my website!