"I speak to the people of my time."
Translation:Ich spreche zu den Menschen meiner Zeit.
mit takes a dative so it would be "mit der Leute". Maybe here there is also difference between "talking with" and "talking to". I don't remember the sentence about talking to plants, but it would make sense that someone would talk to plants, but not with plants... I would think this question would be analogous though. Not sure.