Sentence:  When in one letter Jessica informed me that her father did not like the <WSD>idea</WSD> of her going out alone on New Year's Eve , I knew for a moment an immense relief ; but the letter went on : she had cried , she had implored , she had been miserable at his refusal , and finally he had relented - and now how happy she was , how expectant ! 
Meaning of the word marked with <WSD> tags:  the content of cognition; the main thing you are thinking about