Thought is the property of him who can entertain it, and of him who can adequately place it.

An idea belongs to whoever can actually hold it and to whoever can put it where it does some good. Having had it first counts for less than people assume. Plenty of valuable thinking sits unused in the mind that produced it because that person could not find its application, and someone else who understood where it fitted made it matter.

Worry less about whose idea something is and more about whether you can place it well. If a good thought is going nowhere in your hands, give it to someone who can use it. And when you take one up, do the work of finding where it belongs.