Kissing Science Library and Kissing Nature are two different series. If you already have a pro-science library, whether you need to buy pro-science depends on your interest and demand for natural science. Kissing nature series mainly covers plants, animals, weather and other aspects of nature, helping children understand the laws of nature and protect the environment. If you are interested in these topics and want to know more about them, it may be a good choice to buy a pro-nature series. But if you are not interested in these topics, or you already have other similar book resources, then there may be no need to buy pro-nature series. The final decision still depends on your personal situation and preferences.