Hi Ron,
I just went through this post and found it very helpful. By the way, I have two ideas to talk about. Hope you can kindly correct me if I am wrong.
First of all, I noticed that "Essential" is a modifier. So if you eliminate it, you can get the sentence " shields with wooden frames are items to protect warriors" . As you explained, I think that shields can not automatically be items to protect warriors unless they are used by people in Africa. You can not say A TOOL IS A PURPOSE. That's why it is NONSENSE to me.
Besides, I got stuck to a problem which occurred to me by Hemant.
"....shields with wooden frames are essential items of military equipment to protect warriors...."
Viewing from a step higher, "...essential.....to protect warriors...."
-Why/for what purpose is it essential?
-To protect the warriors
We know it is correct to say "The problem is difficult to solve" However, here it is still awkward to say " the wooden frames are essential to protect warriors". But we can say "the wooden frames are essential in protecting warrior." OR "It is essential to use the wooden frames to protect warriors."
So my question is : What is the difference between "to protect warriors" and "to solve"? Both of them seem "TO DO" to me.
Hope I clarify my meaning.
Thanks,
One of your fans