For
@Gori the Grey and others who don't have the game yet, a word of explanation.
Each age/era (Antiquity, Exploration, Modern) has exactly 4 legacy paths: Culture, Economy, Military, Science.
Each legacy path has milestones along the way. If you complete a legacy path, you get a specific bonus for the next age.
If you complete a legacy path in the last age, you unlock a victory condition, usually requiring performing some final task.
But each milestone, on each path, in every age, gives a least one bonus.. Those bonuses often include an attribute point to buff your leader.
Choose the right attribute points to make your eventual victory easier, indirectly. Achieving more than one legacy path in a given age gives an in-game achievement, that enables the memento system (topic for another thread) to help your *next* game.
Others will point out that one can win the game without completing any milestones (or paths) in the first two ages.
Technically true, but it's not in the spirit of the game. That type of gameplay doesn't really reflect, "Build something you believe in."