Of the times and moments. That is, of the day of judgment, of the end of the world, of the destruction of Jerusalem. It is enough to know the time is uncertain, and that death cometh as a thief in the night. (Witham) --- When the judgment shall take place the Angels themselves do not know. Perhaps St. Paul, when wrapt up to the third heaven, may have learnt something on this subject; for he was told many things which he could not announce to man; therefore, he says, I need not write to you: it is unnecessary for us to know it. (Calmet)

Overtake you. It is a subject of astonishment, that some people are so childishly afraid of the last day, that they cannot think of it without consternation, lest it should happen in their time. Weak souls! Do they not recollect that death will certainly overtake them, and that will be to them individually the end of the world, and the last day. The whole world then does perish as far as regards them. (Haydock)

You are the children of light. That is, there is little danger of thieves in the day time, when it is light. Also watch and have arms to defend you, the coat of mail of faith; the helmet of hope: you are under the protection of Christ, who died for you, and for your salvation. See St. John Chrysostom, p. 293, &c. (Witham)

1Th 5:8 Christian's panoply is not faith alone, but faith, hope and charity, as we see here.

Whether we wake or sleep. That is, whether we be of the number of those whom Jesus Christ shall find still upon earth, when he shall come to judgment, or among those who have slept and returned to dust, it is his will that we should be his. (Theodoret)

Rebuke, or correct the unquiet.[1] By the Greek, it signifies the disorderly, or those that keep no order. (Witham)

===============================

[BIBLIOGRAPHY]

The unquiet: inquietos, Greek: ataktous, inordinatos, sine ordine et regula viventes.

====================

Always rejoice. It is usual for St. Paul to recommend joy to the faithful. Cheerfulness is indeed the characteristic of true virtue, which by no means consists in, nor encourages, sourness or moroseness, as some mistaken people imagine. God loves a cheerful giver. Sorrow, which is of this world, killeth. (Haydock)

1Th 5:19 not oppose either the interior gifts of the holy Spirit, which are his graces, nor his exterior gifts of prophecy, &c. Take the regular precautions of prudence, that you be not deceived by those who pretend to be inspired; but when satisfied that the inspiration comes from heaven, do not despise it. Be like good bankers, take the good coin, and reject the counterfeit. (St. Cyril of Alexandria)

Prove all things. That is, examine prophecies whether they be true, and the doctrine which you hear from new preachers, and refrain yourselves not only from evil, but from every thing that hat the appearance of evil, and which may disedify and scandalize others. (Witham) --- Hold that which his good. This we can best learn from the doctrine of the apostles, and the spirit of the Catholic Church. Men can deceive and be deceived, but the Spirit of God, speaking to us by his Church, can neither deceive us nor be deceived.

Spirit, and soul. The former marks the understanding, the latter the will: hence these two terms give the two principal faculties of the soul. (Bible de Vence)