The paper presents a framework for understanding economic complexity by analyzing trade data as a bipartite network, where countries are connected to the products they export. It argues that economic complexity is a key determinant of a country's level of income and growth potential. The authors propose a method called the Method of Reflections to quantify economic complexity by characterizing the structure of this network. They show that the complexity of a country's economy is correlated with its income and that deviations from this relationship predict future growth. This suggests that countries tend to converge to income levels dictated by the complexity of their productive structures. The authors also demonstrate that the complexity of a country's economy predicts the types of products it can develop in the future, indicating that the availability of capabilities is crucial for economic development. They validate their measures by showing that they are strongly correlated with the diversity of labor inputs used in production. The paper also introduces a minimalistic model to simulate the relationship between capabilities and product production, showing that countries with more capabilities are more diversified and produce less ubiquitous products. The study further shows that the evolution of a country's productive structure exhibits path dependence, meaning that a country's future exports depend on its current productive structure. This is consistent with the idea that the productive structure of countries evolves by spreading to "nearby" products in the Product Space, which is a projection of the bipartite network studied here. The results suggest that the proximity between products in the Product Space is related to the similarity of the capabilities required to produce them. The paper concludes that economic complexity is a key factor in development, and that measures of economic complexity can provide valuable insights into a country's potential for growth and development. The authors argue that development strategies should focus on generating the conditions that allow complexity to emerge, as this is essential for sustained growth and prosperity. The study also highlights the importance of considering the specific capabilities and their complementarity in development economics, rather than relying on aggregate measures of physical or human capital.The paper presents a framework for understanding economic complexity by analyzing trade data as a bipartite network, where countries are connected to the products they export. It argues that economic complexity is a key determinant of a country's level of income and growth potential. The authors propose a method called the Method of Reflections to quantify economic complexity by characterizing the structure of this network. They show that the complexity of a country's economy is correlated with its income and that deviations from this relationship predict future growth. This suggests that countries tend to converge to income levels dictated by the complexity of their productive structures. The authors also demonstrate that the complexity of a country's economy predicts the types of products it can develop in the future, indicating that the availability of capabilities is crucial for economic development. They validate their measures by showing that they are strongly correlated with the diversity of labor inputs used in production. The paper also introduces a minimalistic model to simulate the relationship between capabilities and product production, showing that countries with more capabilities are more diversified and produce less ubiquitous products. The study further shows that the evolution of a country's productive structure exhibits path dependence, meaning that a country's future exports depend on its current productive structure. This is consistent with the idea that the productive structure of countries evolves by spreading to "nearby" products in the Product Space, which is a projection of the bipartite network studied here. The results suggest that the proximity between products in the Product Space is related to the similarity of the capabilities required to produce them. The paper concludes that economic complexity is a key factor in development, and that measures of economic complexity can provide valuable insights into a country's potential for growth and development. The authors argue that development strategies should focus on generating the conditions that allow complexity to emerge, as this is essential for sustained growth and prosperity. The study also highlights the importance of considering the specific capabilities and their complementarity in development economics, rather than relying on aggregate measures of physical or human capital.