Full Idea
Grotius said there was a minimum core of morality (based on self-preservation), and disregarded the elaborate accounts of principles of natural law which Aristotelians had always sought to develop.
Gist of Idea
Grotius ignored elaborate natural law theories, preferring a basic right of self-preservation
Source
report of Hugo Grotius (On the Law of War and Peace [1625]) by Richard Tuck - Hobbes Ch.1
Book Reference
Tuck,Richard: 'Hobbes: a very short introduction' [OUP 2002], p.26
A Reaction
Aquinas would be the key Aristotelian here. I tend towards the Aristotelian view. If you go for the minimal view, it is not clear why there is a 'right' to self-preservation, rather than a mere desire for it.