Romeo’s behavior was modeled by the differential equation dR/dt = aJ. This equation describes how Romeo’s love (represented by R) changes in the next instant (represented by dt). The amount of change (dR) is just a multiple (a) of Juliet’s current love (J) for him. This equation idealizes what we already know – that Romeo’s love goes up when Juliet loves him – by assuming something much stronger. It says that Romeo’s love increases in direct linear proportion to how much Juliet loves him. This assumption of linearity is not emotionally realistic, but it makes the subsequent analysis much easier. Juliet’s behavior, on the other hand, was modeled by the equation dJ/dt = -bR. The negative sign in front of the constant b reflects her tendency to cool off when Romeo is hot for her. Given these equations and an assumption about how the lovers felt about each other initially (R and J at