Instruct: Classify the given Amazon review as either positive or negative.
Query: Best book I have seen for this

This book is incredible--it shows everything, including the hormones for both genders! (Useful for teaching how things work!)I had a copy of an earlier version, which I used to show my older children why their younger siblings "weren't there yet"--and why the baby "wasn't done yet". They learned a great deal about how we develop and how things work (and so did I). This was a very good book in every respect, and Lennart Nilsson deserves a lot of praise for taking the time and effort to compile this. He will have a profound influence on an entire generation in learning.