Dream

Kimihiro Watanuki saw Clow Reed in the dream. Black Mokona sense something on Watanuki and he decides to sleep with Watanuki. When Watanuki is sleeping already, Black Mokona sense something again and Black Mokona sees Watanuki glows and conjures Clow Reed's magic circle. Why Watanuki sees Clow Reed in the dream? Why Clow Reed wants to meet with Watanuki?