Taking notes when studying books are much faster

I realize if i take notes when studying Oracle it is much faster to absorb.

I have read Sybex OCA study guide a couple of times but still missed out a lot of details. Only now that i start copy pasting notes from the pdf to words, that i start remembering the details.

Probably it is like digging for diamond in a pile of ash, putting the diamonds into a box can help to refer them later much faster, like indexing, instead of looking back into the ash again.