All right, some points for Rinnie

:
(1) You have asked what Zen can do that prayer cannot. The answer is very simple, and threefold (I’m adding one from my answer earlier): (1) perceptual clarity about the world (useful tool for philosophy), (2) Calmness of mind, and (3) Satori (an instantaneous insight about something that cannot be expressed in words).
Prayer can give (2), but that is not the purpose of prayer. And while you may end up doing good philosophy while praying, that is not the purpose of prayer either, and it would mean you are being distracted at prayer.
(2) You complained I was “arguing with myself” for making a distinction between “meditation” as the first stage of mental prayer and “meditation” as a form of relaxation. This really isn’t a tough distinction to make. St. Thomas Aquinas answered most of his objections by making a distinction. If you’re going to refuse to make simple distinctions then continuing to debate the point is going to be pretty useless. Making distinctions is necessary for clarity of thought - and it’s not hard.
Zen isn’t a spiritual practice; we don’t need it for salvation. It’s like physics, or exercise. We do it because we enjoy it, and it may be good for us, and it may even (hypothetically) be necessary for something, but not (directly) necessary for salvation. No need or reason for the Church to teach it.
If you sincerely hold exactly what you said than you are committing a heresy. As Catholics we believe in both faith and reason, that God wrote two books for us - nature and Scripture. We do NOT have natural knowledge about the world revealed to us - we have to go out and discover it. Best example of this is science. Science wasn’t revealed to us in prayer. And it tells us everything we know about the natural world - so much, in fact, that it would take many lifetimes for any individual to learn and grasp it all (why we have to have specialization - mine is astroparticle theory, the intersection between theoretical astrophysics and high-energy physics).
We have it taught to us by human sources, just as everything is taught to us by human sources. Your prayer is taught to you by your priest, or by your family if you are a cradle Catholic - not by Christ.
Zen is a school of Buddhism. Buddhism is not equivalent to the New Age Movement, a loose term that usually refers to Theosophy (which has no connection with authentic Buddhism whatsoever) or Wicca (no relation whatsoever) or groups and practices inspired by those two. Yoga is a Hindu (not Buddhist) practice.
Following Henri de Lubac, I do not regard something as automatically “non-Catholic” if it is “Buddhist” or something from any other religion. As Lubac pointed out, Christianity is
sui generis, not just one religion among others - and so “religion” cannot be predicated univocally of Christianity and Buddhism. Upon further reflection, I also note that an entire religion with a well-developed creed and set of rituals and moral code - Neo-Platonism (
yes, they did have their own priests and form worship) - was completely subsumed by Christianity, to the point where we think of it as simply an intellectual plank in Christian philosophy. Why not do the same with Buddhism?
Christian prayer is not lacking anything. That isn’t going to stop me from reading novels, or doing physics, or practicing Zen. They all fill different needs.
Jesus and Buddha are different and make radically different claims. Recognizing that fact is a bit more tactful (and much more insightful) than ridiculing Buddhism.
I was going to wish you a blessed Great and Holy Friday, but the clock turned midnight. It’s Holy Saturday now. Have a blessed remainder to your Triduum!