The opening of this week's Torah section is 'Jacob sent malachim'. Commentators debate the meaning of this last word, however many agree that it should be translated as 'angels' and not simply 'messengers'.
In fact, Rashi (Rabbi Shlomo ben Yitzchak, 1040-1105), one of the leading commentators on the Torah, explicitly states that they were 'truly angels'. The Maggid of Mezritch (1704-1772) explains that Rashi wants to teach us, in addition to the meaning of the word, something fundamental to the Jewish perspective on how to face the world around us.
When Jacob went to meet his brother Esau, he sent angels to try to persuade him to put aside their differences. However, Jacob didn't simply send angels; he sent 'angels in truth (mamash - in Hebrew)'—that is, the physical, material aspect of angels, while their spiritual aspect remained with Jacob. The success of the angels' mission depended on their remaining spiritually united with Esau even while they were with him.
And herein lies the secret to the success of the Jewish people's mission on earth, to refine and elevate the world to make it a place fit for the revelation of the Divine Presence: when one becomes involved with Eisav, that is, with the whirlwind of daily worldly life, with work, etc., one must know that one's success depends exclusively on always being connected to one's source, to God, in order to have the strength to overcome life's difficulties.