In one of the renowned grammar books I've come across an example of confusing usage of the perfect infinitive, where in my opinion past perfect should be used instead:
He is thought to have been deeply depressed at the time, but recovered later.
The above sentence is placed in the past, so why there is perfect infinitive? I'd say the following sentence is more logical:
He is thought to had been deeply depressed at that time, but recovered later.
Can anybody explain it to me, please?