Good ideas can come from many sources, including nature, other ideas, culture, and biology. They often start as hunches that develop over time through contemplation and by colliding with other hunches in dense populations and networks. Cities and liquid networks allow ideas to spread and recombine in new ways, leading to innovation. While error and serendipity can play a role, good ideas generally follow patterns of building on existing foundations and sharing developmental timelines over decades from inception to widespread adoption.