"As I noted in my Nobel lecture, an early insight in my work on the economics of information concerned the problem of appropriability - the difficulty that those who pay for information have in getting returns"

Joseph Stiglitz's quote is describing the concept of appropriability, which is the difficulty of those who spend for information to get returns on their investment. This concept is very important in the economics of details, which Stiglitz has actually studied thoroughly. In his Nobel lecture, Stiglitz noted that this was an early insight in his work. Appropriability is a major problem in the info economy, as it can be hard for those who spend for details to gain from it. This is due to the fact that details can be easily shared and copied, making it hard to control who has access to it. Stiglitz's work has actually assisted to clarify this issue and has offered valuable insights into the economics of info.