I remember learning a story in the Talmud (I think) and am trying to find the source. I'm a little fuzzy on the details, but this is what I remember.
There was a Talmudic Rabbi who was sold into slavery, and was being taken by his new master to Rome.
On the way, the Rabbi told his new owner that traveling in front of them were a Jew and a non-Jew (possibly slaves), a donkey and another animal (I can't remember which), and one was carrying oil and one water. There may have been some other details that the Rabbi told his owner as well.
When this was proven to be true, the owner was so impressed that he told the Rabbi that if he would tell him how he was able to know this, the owner would set the Rabbi free.
The Rabbi told him that he had deduced it based on various clues. He pointed out that there were two drip patterns. One had absorbed in the ground (water) and one hadn't (oil). He pointed out that one of the people had gone off the path to relieve himself, which is a Jewish trait, while the other person hadn't. (He probably pointed out some other things as well)
That's what I remember; anyone have a source?