Cell and Piccolo in “Unfinished Business”

Cell

The computer told me one more thing. Once I have absorbed the other androids, I will be the most powerful being who has ever lived.

Piccolo

But what for? You were already the strongest creature alive in your time.

Cell

This is true. But my design was meant to include the powers of Androids 17 and 18. Without them I can never be complete. I had to seek them out. It's what I was created to do. Of course, it may also be the blood of Vegeta and Frieza coursing through my veins which fuels my desire for more power.