There is no greater joy than having a child. From a religious perspective, bringing new life into this world is the most tangible way of demonstrating that we were created in G-d’s image. The initial biblical portrayal of G-d is that of a Creator. And the first mitzvah given to man is to be fruitful and multiply and to conquer the earth, mandating us to imitate and partner with G-d in the continuing process of creation. The Torah describes the great joy, and the subsequent party, when Yitzchak was born. A primary theme of sefer Breisheet is the yearning for children.
It is hard to imagine a more disparate couple than Yitzchak and Rivka, the quiet contemplative husband who would "meditate in the fields" (24:63), and the worldly, independent-thinking wife who “ran again to the well” (Breisheet 20:24). Yitzchak spent his entire life in the land of Israel, never traveling the world. He was, as our Sages describe him, "a pure offering", ready to sacrifice himself to G-d. He could see no evil in others, and thus could be easily fooled by both Eisav and Yaakov.