“Heaven is not a place, and it's not a time. Heaven is being perfect.”

554-556
Fruits of Solitude (1682), Part I
Context: Love is indeed Heaven upon Earth; since Heaven above would not be Heaven without it: For where there is not Love; there is Fear: But perfect Love casts out Fear. And yet we naturally fear most to offend what we most Love. What we Love, we'll Hear; what we Love, we'll Trust; and what we Love, we'll serve, ay, and suffer for too. If you love me says our Blessed Redeemer) keep my Commandments. Why? Why then he'll Love us; then we shall be his Friends; then he'll send us the Comforter; then whatsover we ask, we shall receive; and then where he is we shall be also, and that for ever. Behold the Fruits of Love; the Power, Vertue, Benefit and Beauty of Love! Love is above all; and when it prevails in us all, we shall all be Lovely, and in Love with God and one with another.

Source: Of Mystics & Mistakes

Source: Heaven Revealed (Moody, 2011), p. 19

Source: Midnight Alley

"On the Literary Character" (28 October 1813)
The Round Table (1815-1817)

Supplement, Q98, Article 4
Note: This Supplement to the Third Part was compiled after Aquinas's death by Regnald of Piperno, out of material from Aquinas's much earlier "Commentary on the Sentences".
Summa Theologica (1265–1274)
Context: Even as in the blessed in heaven there will be most perfect charity, so in the damned there will be the most perfect hate. Wherefore as the saints will rejoice in all goods, so will the damned grieve for all goods. Consequently the sight of the happiness of the saints will give them very great pain; hence it is written (Isaiah 26:11): "Let the envious people see and be confounded, and let fire devour Thy enemies." Therefore they will wish all the good were damned.

Source: The Light of Day (1900), Ch. III: Science and Theology

Section 2, member 4, Exercise rectified of Body and Mind.
The Anatomy of Melancholy (1621), Part II