Some philosophic systems lost their vitality and became wholly congealed.有些哲学体系失去了生命力，变得完全僵化了。These ideas formed the core of his philosophy.这些思想构成了他哲学体系的核心。Eugenics was the central, and most controversial, part of his social philosophy.优生学是他社会哲学体系的中心问题，也是最具争议性的问题。