 Yet Salmon found causality ubiquitous in scientific explanation, which identifies not only natural laws (empirical regularities), but accounts for them via nature's structure and thereby involves the ontic (concerning reality), how the phenomenon "fits into the causal nexus" of the world (Salmon's causal/mechanical explanation).For instance, Boyle's law relates temperature, pressure, and volume of an ideal gas (epistemic), but this was later reduced to laws of statistical mechanics via average kinetic energy of colliding molecules composing the gas (ontic).Thus, Salmon finds scientific explanation to be not merely "nomological"—that is, lawlike—but rather ontological, or "causal/mechanical".