Quote Originally Posted by David L. View Post
If I tell someone some very bad news, I can anticipate some emotional reaction, such as sadness, tears etc. But if they just shrug their shoulders, or if they laugh, then I would be surprised at their reaction - it was not what I had expected.

What say I don't think I'm very popular at work. At morning tea one day, they all gather round and sing "Happy Birthday" and they've got a cake. I had no idea they would do this - I was surprised by their thoughtfulness- I was taken completely unawares.
This is the same meaning when we say, "The cowboys were ambushed by the Indians" - the cowboys had no idea the Indians were lying in wait, ready to attack.

If I said, "I was surprised at their thoughtfulness", then it would mean, I considered them self-centred, ungenerous souls and so would not expect any milk of human kindness from them - but they did! - so I am surprised at their action. It was the opposite of what I thought - I considered them a thoughtless lot who couldn't care less it was my birthday.

"Hollywood surprised by Cruise/Kidman Split."
versus
"Hollywood surprised at Cruise/Kidman Split."
Cruise and Kidman had been married for many years and seemed a perfect couple. No rumours of problems in the marriage. So Hollywood is shocked and taken by surprise when it is announced, they are to split.
compare
Cruise and Kidman had been married for many years. They are both Scientologists. They had been seen rowing in public, and there had been rumours that they were seeing a Marriage Counsellor. But (say) Scientology is like Catholicism - they do not believe in divorce. So Hollywood expects they are just having a bumpy patch. But no - Hollywood is surprised at their decision to defy their Church and get a divorce. EVen if not totally happy, they expected them to stick together because of the teachings of their 'religion'.

Can you see the difference? Have a try, and we'll discuss further.
Let me check if I understood you right.
I had never thought about the matter, so I was surprised by what had happened.
I had thought the matter would have a different outcome, so I was surprised at what had happened.

1. Assume you expected a person to arrive, but you didn't expect him to arrive so early. What would you choose to say:
I was surprised by/at his early arrival.

2. Assume you didn't expect a person to arrive. What would you choose to say:
I was surprised by/at his arrival.