Those who lived in the days of Noah and Abraham were more like the angels in form, in comeliness and strength. But every generation has been growing weaker.—Spiritual Gifts 1:69. TA 69.1
More than one hundred years before the flood the Lord sent an angel to faithful Noah to make known to him that He would no longer have mercy upon the corrupt race. But He would not have them ignorant of His design. He would instruct Noah, and make him a faithful preacher to warn the world of its coming destruction, that the inhabitants of the earth might be left without excuse.... TA 69.2
Angels were sent to collect from the forest and field the beasts which God had created.—The Spirit of Prophecy 1:69, 72. TA 69.3
Angels went before these animals and they followed two and two, male and female, and clean beasts by sevens.—Spiritual Gifts 3:67. TA 69.4
Everything was now ready for the closing of the ark, which could not have been done by Noah from within. An angel is seen by the scoffing multitude descending from heaven, clothed with brightness like the lightning. He closes that massive outer door, and then takes his course upward to heaven again.—The Spirit of Prophecy 1:72. TA 69.5