Let us not, therefore, know God by halves or make his lovingkindness an excuse for our indolence; for this, his thunders, for this, his lightnings—that his goodness may not be held in despite. He who causes the sun to rise also strikes people with blindness. He who sends the rain also causes the rain of fire. By the one he manifests his goodness; by the other, his severity. For the one let us love him, for the other let us fear, that it may not be said also to us, “Or despise you the riches of his goodness and patience and longsuffering? Know you not that the mercy of God leads you to repentance? But according to your hardness and impenitent heart, you treasure up to yourself wrath against the day of wrath.”
Source: THE LONG RULES, PREFACE