Causation can be reduced to transmission in the following way: (K) Two events c and e are linked as cause and effect iff there is a conserved quantity P which is exemplified in both events and of which an amount Q is transferred from c to e. This conception permits to overcome difficulties faced by earlier versions of the transference theory and by "process theories" of causation, such as Salmon's and Dowe's. In particular, it can explain the asymmetry of causality without relying on the asymmetry of time, and the difference between causal and pseudo-processes.