Определение и Значение "on one's mind "

What is the origin of the idiom "on one's mind" and when to use it?

The idiom "on one's mind" originated from the concept of thoughts and concerns occupying a person's mental space or preoccupying their thoughts. It signifies the presence of a specific topic, worry, or issue that is prominent in an individual's thinking and attention. The phrase is used to emphasize the mental focus and significance of the subject matter, suggesting that it is actively occupying the person's thoughts and influencing their state of mind.