It is contended that since causality is originally a metaphysical principle, it should be possible, in general, to formulate physical theories without recourse to this principle. The best known example for such an approach might be the theory of action at a distance, where the description of physical phenomena naturally takes an unfamiliar, non-causal form. The Machian aspect inherent in this approach is emphasized. The recent discovery of violation of time-reversal symmetry of the fundamental physical laws is discussed from the above viewpoint. It is hoped that this kind of non-causal approach will enable us to study some further aspects of time which otherwise are masked by, and intermingled with, causality.