This article explores the affective language used to describe colour by three key members of the early Royal Society of London – Robert Boyle, John Ray, and Francis Willughby. In so doing, we will encounter a paradox. On the one hand, Boyle and his contemporaries understood that colour arose in part from the reactions of their own bodies to external things. It surely stood to reason, therefore, that quieting down the most unruly and subjective components of those reactions – and few were more unruly than some of the passions inspired by beautiful colours – was the best way to make colours scientifically useful. On the other hand, those same philosophers insisted that their subjective responses could sometimes be scientifically significant. Far from trying to eliminate the passions raised by lovely colours, Boyle and his contemporaries sometimes treated those subjective responses as useful tools for philosophical inquiry.