The human mind.
You actually make a very good point. A 1000 years ago, if you asked some rich guy to do something whether build a bridge or teach his kids math or fuck his wife (cuz he was busy fucking his much younger other wife) all he would have to do is point at one of his numerous servants to do it for him.
He probably wouldn't care to understand "processor speed or RAM" when he could have an actual person just do the work for him; EZ PZ!