be kind

Ian MacLaren, a noted Scotsman, author of “Beside the Bonnie Brier Bush,” cared deeply about those around him. His oft-quoted words offer wise counsel: “Be kind. Everyone you meet is carrying a heavy burden.”

Ian MacLaren was the pseudonym or pen name of Rev. John Watson. Wikipedia has an entry for MacLaren. His book “Beside the Bonnie Brier Bush” was a best seller in the 1890s. In 1965 in the Chicago Tribune the words attributed to Ian MacLaren are a close match to the quotation we are tracing [CTM]:

"Most of us are acutely aware of our own struggles and we are preoccupied with our own problems. We sympathize with ourselves because we see our own difficulties so clearly. But Ian MacLaren noted wisely, “Let us be kind to one another, for most of us are fighting a hard battle.”
http://quoteinvestigator.com/2010/06/29/be-kind/