Accordingly, had Adam HaRishon waited until Shabbas eve to make kiddush on the wine, he would have merited serving Hashem with the simchah associated with the performance of a mitzvah—involving only the one heart associated with the yetzer tov. The "nachash hakadmoni," the yetzer hara and all of its forces, would have remained stranded outside the boundaries of kedushah without any simchah. As forces of tumah, they possess no association with simchah but are associated only with sadness, grief and heartache.
Yet, by following the advice of the nachash and drinking from the wine that Chava prepared for him on the weekday, the words of the passuk were fulfilled: "ויין ישמח לבב אנוש". The yetzer hara entered his heart; so, instead of one heart, he ended up with two hearts—a yetzer tov and a yetzer hara. This accords with Rashi’s comment (Bereishis 2, 25): "ואף על פי שניתנה בו דעה לקרות שמות, לא נתן בו יצר הרע עד אכלו מן העץ ונכנס בו"—even though he was endowed with the knowledge to assign names, the yetzer hara was not placed in him until he ate from the tree; and it entered his being. So, we learn that the yetzer hara entered man’s heart after the "cheit Eitz HaDa’as." That was the effect of the contamination and filth with which the nachash infected man and all of creation.
At the very same time that the nachash—the yetzer hara—succeeded in entering man’s heart, it stole the simchah of mitzvah from him. In its place, it introduced a licentious form of simchah that encourages and thrives on wrongdoing, in keeping with the notion of: "ויין ישמח לבב אנוש". As explained, this form of simchah is only fleeting and ultimately leads to grief and heartache, in accordance with the decree that man must die. Ever since then, it has been incumbent upon us to extract the simchah from the yetzer hara by using the attribute of simchah to celebrate and rejoice in the study of Torah.
