I saw a beautiful Vort this past week in a sefer Shaarei Ahron. He quotes Rav Dessler, who said in the name of his father, regarding the 15th Mishna of the first Perek of Avos. Shammai says:
והוי מקבל את כל האדם בסבר פנים יפות
One should greet every individual cheerfully.
Yet we don't Pasken like Bais Shammai, so why is this said over in his name?
The answer is that if it were Hillel who said it, people would say that it is only a Midas Chassidus, being that Hillel was always so patient with everyone and always went לפנים משורת הדין.
ולבן שנים מחלב אל תיקרי לבן שינים אלא לבן שנים פשטיה דקרא במאי כתיב כי אתא רב דימי אמר אמרה כנסת ישראל לפני הקב"ה רבונו של עולם רמוז בעיניך דבסים מחמרא ואחוי לי שיניך דבסים מחלבא מסייע ליה לר' יוחנן דאמר ר' יוחנן טוב המלבין שינים לחבירו יותר ממשקהו חלב שנאמר ולבן שנים מחלב אל תקרי לבן שינים אלא לבון שינים
The Gemara in Kesuvos 111B says that "teeth are preferred over milk". In other words, if you meet a person, he would rather that you greet him with a warm smile than present him with a cold cup of milk.
I've often wondered how one would be able to be Mekayem Shammai's dictum. Perhaps in the shtetlach and small towns of yesteryear one would be able to greet all passersby; but in our day and age, particularly Manhattan's pedestrian traffic, this becomes an impossibility.
Yet if we follow Shammai's words, all is clear. We need to keep a perpetual smile on our faces when we are seen in public. Everyone who passes us by will then have a lift in their day.
