This poem has many themes but an important one is Wisdom - or the lack of it. Being foolish, or acting without prudence or reasoning can lead people into chaos or into a situation where they lose all that they have. The nymph uses this fear as a reason to reject the shepherd. She seems to mistrust the gay abandonment of springtime feelings when the warm sun first comes out after a depressingly grey and freezing winter when everyone has to cover up with many layers. Instead of welcoming the joy that everyone feels when springtime feelings make everyone feel happy, she seeems to be suspicious of it, perhaps thinking that it will lead to all sorts of trouble where people stop thinking clearly and reasoning decisions rationally. She thinks that this is just like the folly of being in love and that,by Fall there will be consequences for their silly choices - and they won't be good! It seems that she rejects the shepherd 'just in case.' She is worried that 'following one's heart' and not one's 'reason' is a recipe for disaster. Perhaps a balance, however, it's what's needed.