In the Rothman's causal pie model, a causal component is a factor that acts concertedly with others to produce a sufficient cause (i.e disease) and that a causal component that is common to every sufficient cause is termed a necessary cause for that sufficient cause. Given the role played by 'time' in the development of all human diseases, is 'time' a necessary cause? Do we really need to consider time in the Rothman's causal pie model since it is a common factor to all human disease?