Clarke's Law

Actually, the third of three dictums, Clarke's Law states that:

Any sufficiently advanced technology is indistinguishable from magic.

The reverse could also apply, too. (DW: Battlefield).

To use but one example, the Sycorax thought of blood control as form of sorcery and the Doctor as a user of witchcraft. (DW: The Christmas Invasion)

Direct reference
The Doctor reminded Ace of Clarke's Law. (DW: Battlefield).

Indirect reference
The Captain said his now-wrecked craft had posessed technologies "indistinguishable from magic" (DW: The Pirate Planet).