It is altogether unlawful to kill oneself... Wherefore suicide is contrary to the inclination of nature, and to charity whereby every man should love himself... Life is God's gift to man, and is subject to His power, Who kills and makes to live. Hence whoever takes his own life, sins against God... for it belongs to God alone to pronounce sentence of death and life.
Thomas AquinasWe can't have full knowledge all at once. We must start by believing; then afterwards we may be led on to master the evidence for ourselves.
Thomas AquinasGive us, O Lord, a steadfast heart, which no unworthy affection may drag downwards; give us an unconquered heart, which no tribulation can wear out; give us an upright heart, which no unworthy purpose may tempt aside. Bestow upon us also, O Lord our God, understanding to know you, diligence to seek you, wisdom to find you, and a faithfulness that may finally embrace you; through Jesus Christ our Lord.
Thomas Aquinas