In many respects proteins are attractive catalysis to form the basis of renewable technology, but such applications remain limited. Similarly, understanding proteins promises a direct avenue to address a wide range of human diseases, but many medical challenges persist. This situation suggests that fundamental knowledge on proteins remains to be discovered. Two complementary approaches to gain such knowledge are to discover and employ generally applicable principles in protein science and to develop novel methods for studying proteins. In this seminar I will present how spectroscopic studies of photoreceptor proteins are contributing to both of these challenges.