During his time as an English teacher, when a student translated "I love you" into Japanese as literally as "我君ヲ愛ス", he is said to have remarked, "A Japanese person would never say something so unromantic. Translate it as 'The moon sure is beautiful (月が綺麗ですね)', that will get the point across."
Some claim what he actually said was "The moon sure is beautiful when I'm with you.", but no reliable sources for this story have been found in the first place, so there is a high probability that the episode was a literary invention or an urban legend. What can be said with certainty is that this story had spread long before it was popularized on the internet and worldwide web.