Opportunity is the great gift of human society, and how widely spread, how equally distributed it is, defines whether a society is a good or bad place to be.
Market capitalist freedom and socialist equality promise two very different societies but both fall down, if unregulated or unchecked, because opportunity isn't respected as a first principle. Capitalism unregulated results in monopoly and de facto feudal oligarchy, where opportunity is horded by the old and the rich against young and the poor. Socialism unchecked results in orthodoxy and de jure authoritarian statism, where opportunity is distributed without recognizing the individual's freedom and the incentives for excellence and effort are given up in favor of community service and equality of outcome.
The Capitalist Manifesto takes opportunity to be a sacred covenant between society (community) and the citizen (individual). Opportunity must be given to all, equally, according to the individual's effort and excellence. Opportunity means education, security, a baseline of necessity support, a momentum built during childhood for a hard launch into adulthood and a soft landing for old age and infirmity. Opportunity doesn't mean level playing field in the adult world.