Natural knowledge is available through the observation of creation. For example, the scientist can study the smallest atomic particles, the miraculous interior workings of the human body, or the movement of weather patterns across the globe. However, these natural truths discovered through science do not require supernatural grace. The intelligence of the scientist is sufficient for gaining natural knowledge. The First Vatican Council taught that God is often revealed through his creation and observed through human reasoning (First Vatican Council II.1). However, for the human person to know supernatural truths, supernatural grace is required.
Supernatural knowledge can be best comprehended by considering the lives of Catholic Saints. Supernatural grace allows the limited human person to see and understand things that are typically beyond the five senses. This can oftentimes be an intuitive insight that is lacking supportive concrete facts. This supernatural knowledge is considered a revelation or prophecy given by God.
For example, God instructed St. Catherine of Siena in matters which she could not know naturally. This supernatural knowledge given to the Saints was not something they earned or merited themselves. Actually quite the opposite was most likely true. It may have been experienced by the Saints as an incredible heavy cross to carry in life. However, this cross was both given by God’s grace and carried by the gift of God’s grace.
Natural knowledge is limited by human nature whereas supernatural knowledge is limitless and given only by God to achieve His will.