The article discusses the importance of finding the right balance between density and compactness in cities for sustainable urban development. It compares extreme cases of hyper-density like the Kowloon Walled City with more recent optimized quality density developments in Singapore, Sydney, and Vancouver. The key takeaway is that while high-density living can be sustainable, it needs to be balanced with quality green spaces to ensure liveability and well-being in urban areas. The article suggests that different planning approaches are needed to establish an optimal density model for future sustainable cities.