Recent observations of microwave background and type Ⅰa supeovae (SNe Ia) suggest a space-flat and accelerated expansion Universe. On the other hand, observations of supeovae 1997ff reveal that the Universe has undergone a decelerating-accelerating process. Combining these two classes of observations, we present an eteal expanding Universe toy model driven by quintessence. In this picture, the Universe undergoes an endless sequence of accelerating-decelerating cycles.