A Rebbi told us in the name of the Vilna Gaon that we have two ears and one mouth because we should spend more time listening than talking. (Sounds like Epictetus', "We have two ears and one mouth so we can listen twice as much as we speak") Where is this Gra located?
I saw the following quoted as the Vilna Gaon's commentary to Mishlei 11:2:
שעיקר החכמה הוא בהצנועים ששותקין מלומר תורתם ודעתם, רק שומעין מרבותם. כי כאשר הוא יאמר דבריו, לא יוסיף לו כלום, אבל כאשר ישמע מרבו, יוסיף לו דברים. ... ולכן העינים הם שתים, והאזנים הם שתים, לראות בתורה שבכתב ולשמוע בתורה שבעל פה, אבל הפה הוא אחד
Roughly translated: "Wisdom is chiefly found in those who are quiet and opt to learn from their teachers rather than state their own views. For the individual gains nothing from saying aloud his own opinions, but does benefit from listening to his teacher...and therefore there are two eyes to help one see Torah in written form, and two ears to help one hear Torah in verbal form, but only one mouth."