We never have a full demonstration, although there is always an underlying reason for the truth, even if it is only perfectly understood by God, who alone penetrated the infinite series in one stroke of the mind.
When God works miracles, he does not do it in order to supply the wants of nature, but those of grace. Whoever thinks otherwise, must needs have a very mean notion of the wisdom and power of God.
There is a world of created beings – living things, animals, entelechies, and souls – in the least part of matter. Thus there is nothing waste, nothing sterile, nothing dead in the universe; no chaos, no confusions, save in appearance.
We may say, that not only the soul (the mirror of an indestructible universe) is indestructible, but also the animal itself is, although its mechanism is frequently destroyed in parts.
