Leah and Rachel

Dante Gabriel Rossetti 1855

Leah's eyes were tender, but Rachel had beautiful features and a beautiful complexion. [Vayeitzei 29:17]

Rachel represents the approach of tzadikim [righteous individuals] whose lives are totally holy, and Leah, the approach of ba'alei teshuvah [penitents] who elevate the secular world to holiness.

Thus, Rachel was naturally attractive:  ''Rachel had beautiful [facial] features and a beautiful complexion'' - like the tzadik whose character is flawless; whereas Leah cried profusely [see Rashi] alluding to the process of teshuvah.  She was also naturally outgoing [see Rashi 34:1], a talent which helps a person to bring the outside world to the realm of holiness.

''Yaakov was an honest person, dwelling in tents'' [Toldot 25:27], i.e. he busied himself only with matters of holiness - the approach of tzadikim.  Therefore, people said that Yaakov was destined for Rachel, since their characters matched.  Eisav, on the other hand, was an outgoing ''man of the field''. Therefore people said that he would be a good match for Leah, for only the talented, outgoing Leah would have the ability to make Eisav do teshuvah.

Based on Likutei Sichot Lubavitcher Rebbe vol 35 p. 152-3