We begin by asking how far back in the literature we should go when choosing discoveries to build on. In other words, how myopic is science in the age of Google Scholar? By looking at the age distribution of citations and identifying knowledge “hot spots,” we pinpoint the unique combinations of old and relatively new knowledge that are most likely to produce new breakthroughs. In doing so, we see that the way we build on past knowledge follows clear patterns, and we explore how these patterns shape future scientific discourse. We also look at the the impact that a citation’s jump–decay pattern has on the relevance of research over time, finding that all papers have an expiration date and that we can predict that date based on the jump–decay pattern.