Aspect-oriented programming (AOP) has been attracting much attention in the Software Engineering community by advocating that programs should be structured according to programmer concerns, such as "efficient use of memory". However, like other programming paradigms in their early days, AOP hasn't addressed yet earlier phases of software development. In particular, it is still an open question how one identifies aspects early on in the software development process. This paper proposes an answer to this question. Specifically, we show that aspects can be discovered during goal-oriented requirements analysis. Our proposal includes a systematic process for discovering aspects from relationships between functional and non-functional goals. We illustrate the proposed process with a case study adapted from the literature.