what does Emerson mean in his poem Give All to Love?

I think the speaker is saying to love without restraint the one your with, and the transcendental part is in the little note that pops up at the poem’s end on your link. It basically says that when something ends, as when someone leaves, as the poem says that will happen, whether from death or the person finds someone new, welcome it as a change that the life is configuring to allow you and the person leaving to grow and evolve. The last two lines about half gods leaving and full ones coming is I think saying that your life is being lived half-way and is being terminated for a fuller life to come in.

Emerson is saying that love is such an important part of life that you should give up every other ambition in pursuit of it.

Friends, kindred, days,

Estate, good-fame,

Plans, credit and the Muse,

Nothing refuse.

But when you find love, you should never assume that you have any ownership or control over the woman you love (notice how Emerson has silently assumed that his poem talks only to men).

Keep thee to-day,

To-morrow, forever,

Free as an Arab

Of thy beloved.

(Emerson had the odd idea that Muslims were not possessive of their wives. He lived in Concord. He probably hadn’t met many Muslims).

You must give your all to love, and never expect anything in return, because it will all work out OK in the end. When your wife leaves you, you will discover what True Love truly is.

Though thou loved her as thyself,

As a self of purer clay,

Though her parting dims the day,

Stealing grace from all alive;

Heartily know,

When half-gods go Note,

The gods arrive.

https://shorturl.im/aycw6

He was telling us that our idea of love was incomplete and holding back our spiritual growth. A long time ago I thought that love was something that you reserved for some special set of people that you had judged worthy of it. After a while I got to thinking about what Jesus had said about turning the other cheek and loving our neighbor I put the two together and realized that he had made no exceptions in these statements. It became obvious to me that he intended that we exclude no one from the love that we are supposed to be giving. I started thinking about my idea of love and suddenly realized that I had not been loving anyone at all. I had simply been judging everyone and every thing. Judging someone worthy of love is not love, it is only judgment. I actually started to cry when I realized this. I saw just how much of my life I had wasted being judgmental, thinking of myself as a Christian, when I was actually doing just the opposite of what Jesus had asked us to do. I thought about the verse judge not lest ye be judged, and I understood it for the first time. I realized that I have a lot of catching up to do. So many opportunities were wasted. I now try to apply the love that I have for the world in a universal way like Jesus asks us to do. If I start to feel afraid and think that I see someone that I should not love because of something I have thought or heard I try to catch my mistake as soon as possible. I tell myself that I have forgot the truth and have fallen for the same old trick that had cost me so many opportunities to be loving in the past. The horror of this realization is often all that is necessary to bring me back to my senses and make me drop the judgmental nonsense I was thinking. I still have a lot to learn about love, but at least I’m making progress. Love and blessings Your brother don

Give All To Love

It says you should follow your heart in everything you do. It takes courage, but the rewards are great. And if you love someone and they leave you, let them go. Giving your heart is more important than getting love in return. And if you give freely, without trying to own the other person, you will have understood the true meaning of love. As Kahlil Gibran once said, “If you love somebody, let them go, for if they return, they were always yours. And if they don’t, they never were.” The half-god is the loved one. The god is love itself.