(From the "daf bits" series.)
The mishna (a couple pages ago) listed some of the gentiles' festivals that are considered idolatrous, including some having to do with kings. The g'mara then goes on to talk about various gentile kings, including the following story.
When Onkelos son of Kalonymus, a Roman (and maybe a nephew of Titus), converted to Judaism, the emperor sent soldiers to arrest him. Onkelos told them scriptural verses and they, too, converted. The emperor sent another group of soldiers, telling them not to say anything to him. As they were leaving, Onkelos said "let me just tell you an ordinary thing", and proceeded to explain how, unlike an earthly king, the Heavenly King carries light before His people, citing the pillar of fire that led Israel. (With earthly kings, others carry torches for them but they would never carry torches for their subjects.) They, too, converted to Judaism. The emperor sent yet more soldiers, telling them not to enter any conversation with him. They took hold of him, and on the way out he touched the mezuzah on his doorpost and said: a mortal king dwells within and has guards without, but the Holy One Blessed be He guards without while His servants dwell within. They, too, converted, and the emperor sent no more.
Onkelos went on to write a translation of the torah (with a little elaboration) into Aramaic, the common language of the day. Targum Onkelos is printed alongside the Hebrew in many editions today for study.
I've long felt that the ones who quietly inspire are much more effective than the ones who go out and preach trying to win people over to their view. "Show, don't tell" is about more than writing.