Mary wished to be as familiar with Christ now, as she was before His Passion; forgetting, in her joy, that His body was made much more holy by its resurrection. So, Touch Me not, He says, to remind her of this, and make her feel awe in talking with Him. For which reason too He no longer keeps company with His disciples, viz. that they might look upon Him with the greater awe. Again, by saying I have not yet ascended, He shews that He is hastening there. And He who was going to depart and live no more with men, ought not to be regarded with the same feeling that He was before: But go to My brethren, and say unto them, I ascend unto My Father, and your Father; and to My God, and your God.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Hom. lxxxvi. 2