Good point Alex. Is that a typo, possibly misheard, or is it a deliberate 'synth ladies' reference? Systemagic - Sister Magic. As they would say on Big Brother, You decide!
The Moving Finger writes; and, having writ. Moves on: nor all thy Piety nor Wit. Shall lure it back to cancal half a line, Nor all thy Tears wash out a Word of it.