There was a sharp dispute between Yitzchak and Rivka with regard to their twin sons. Between the love that Yitzchak had for Eisav on the one hand, and the love that Rivka had for Yaakov on the other.

The Torah says, "And Yitzchak love Eisav for game was in his mouth, but Rivka loved Yaakov" (Genesis, 25:28). Yitzchak loved Eisav for a reason. That is because Eisav was loyal to his father, he respected his father, he bought food to his father. When it came to the love that Rivka had for Yaakov, no reason is given. It is the natural love that a parent has for a child.

And then with regard to Yitzchak's love for Eisav, we are told Vaye'ehav Yitzchak, 'and Yitzchak loved Eisav' - it is in the past tense. With regard to Rivka the Torah says, VeRivka Ohevet, literally meaning, 'and Rivka loves Yaakov' - it is in the present tense.

We can understand this, through a passage in the Ethics of the Fathers, Pirkei Avot, Chapter 5, Mishna 19. There the Mishnah tells us that when love takes place because of a reason - it depends on 'something'. If that 'something' disappears, then it is possible that the love might disappear as well - that the love might become 'past tense'. However, if there is love which is natural, then that love will endure forever.

'If there is love which is natural, then that love will endure forever.'

From Rivka we learn, that true love in this world is affection with no ulterior motive. It is there in a very sincere way. That is the type that will endure forever.