And while they looked stedfastly toward heaven as he went up, behold, two men stood by them in white apparel;
And, while they looked stedfastly toward heaven - following Him with their eager eyes in rapt amazement. This is stated as part of that resistless evidence of their senses on which their whole subsequent testimony was to rest.
Behold two men ... in white apparel ('white garments') х en (G1722) estheesesi (G2066) leukais (G3022), in the plural, is better supported than the singular of the Received Text, and is adopted by Lachmann and Tischendorf]. They were angels in human form: see Luke 24:4, where the same phraseology is used of angels.