So, I thought that by taking an unrealistically utopian approach, I could keep the business from growing too much. Instead of trying to make it big, I was going to make it small. It was the opposite of ambition, so I had to think in a way that was the opposite of ambitious.
The above paragraph is on page6 of book Anything You Want by Dered Sivers. As for the bold sentence, I can't really understand its grammar. What I was taught in China is that the object of a preposition is always noun or pronoun. But in the last sentence, the preposition sits before an adjective－ambitious. How could this happen here?
I assume that there are two possibilities, but I'm not sure which one is grammatically correct.
1, There is an ellipsis of word being, so the sentence should be like 'It was the opposite of ambition, so I had to think in a way that was the opposite of being ambitious.' (but it seems the meaning is totally changed from what it was.)
2, The ellipsis is the noun after ambitious, and then it should be "It was the opposite of ambition, so I had to think in a way that was the opposite of an ambitious way. (I personally think this may be the correct on, but not really sure)
Is this usage a proper grammar way, or it's just informal, that preposition sits before an adjective?