Steve Jobs used 190 point font sized text on his slides. He was pretty good at communicating the purpose behind his ideas.
Watch this intriguing conversation between Carmine Gallo and Guy Kawasaki - both extremely accomplished and authentic individuals who have influenced and persuaded millions.
I particularly like Guy's approach : "public-speaking and communication skills are crucial for everyone to develop if they wish to stand out and get ahead professionally. “It’s an essential skill, and the higher you go, the more important it is. How else do you change the world, dent the universe, influence and persuade, and change people's hearts minds and actions?”
Guy also explains how the massive font size enhanced the impact of Steve Job's ideas and message.
Definitely worth watching to improve the impact and influence of your own ideas.