thankful (to do something) I was thankful to see they’d all arrived
safely.
thankful (for something) He wasn’t badly hurt—that’s
something to be thankful for.
(OALD)I suppose that the first infinitive is the complement of thankful. See is preceding or the same time as the main clause.
The second infinitive is the post-modifier, Be thankful for is following or at the same time as the previous clause.
Does the syntactic difference make the semantic difference of infinitives?
(By any chance does the second infinitive contain the meaning of what one should do?)
Answer
There isn’t any difference, since the meaning of thankful is “pleased about something good that has happened, or something bad that has not happened” in both the cases.
What changes is that in “thankful (to do something)” what follows thankful still has the same subject.
Michael was thankful to arrive home safe. Michael arrived home safe, and he was thankful for that.
What follows thankful in “thankful (for something)” is something for which be thankful.
She was thankful for the darkness which allowed her to slip away unnoticed. The darkness allowed her to slip away unnoticed, and she was thankful for that.
She is thankful for being married to the richest man of the state. She is married to the richest man of the state, and she is thankful for that.
Attribution
Source : Link , Question Author : Listenever , Answer Author : apaderno
