A few days ago, one of my colleagues told me that he was stealing some of my ideas to use in his class.
I replied that if he stole something from me, such as my money, then I would no longer have the money. But I still have my ideas. So he can't be stealing them.
OK, he said. He was borrowing my ideas.
But if he was borrowing them, surely he should give them back to me one day?
I feel that the idea of stealing or borrowing ideas is misplaced; and I suggest that he was using my ideas, but not stealing or borrowing.
Finally, there is no need to apologise for it, or even tell me. If someone finds something I do useful, then use it. And you don't need to tell me about it.
I realise that people get very sensitive about other people using their ideas; but I honestly don't see what the problem is. I am delighted if something I do or some idea I have can be of help to others.