Hi,

be of + noun = be adjective

Question:
I think that be of + a noun will have the same meaning as be + an adjective.
I think the following pairs of sentences should have the same meanings.
Could you please show me a web page that explain such idea?

Pair1:
a) The book is of great value to students of history.
b) This book is very valuable to students of history.

Pair2:
 c) They are of great help for learners.
d) They are very helpful for learners.

Thanks