A critical analysis of what was said pointed out the contradictions.
- Explanations of sacrifice, as of other rites, are naturally not wanting among the peoples who have practised or still practise it; but they are often of the nature of aetiological myths and give no clue to the original meaning.
At the present time we are quite uncertain what is the ultimate cause of new growths; in all probability there may be one or more aetiological factors at play disturbing that perfect condition of equilibrium of normal tissues.
The study of epidemic and endemic diseases generally has brought to light an array of facts which very strongly suggest that an intimate association exists between the soil and the appearance and propagation of certain diseases; but although experiments and observations allow this view to be looked upon as well established, still the precise role played by the soil in an aetiological respect is by no means so well understood as to make it possible to separate the factors and dogmatize on their effects.
According to Roscher (in his Lexikon der Mythologie), who identifies the ciris with the heron, the story of Nisus and Scylla (like these of Acdon, Procne, Philomela and Tereus) was invented to give an aetiological explanation of the characteristics of certain birds.