Because the flowers blooming
In our original home
Are everlasting,
Though springtimes may come and go
Their colors do not fade

It is said that although sitting takes place in space and time, it is not bound by space and time. The original home is a simple abode of not identifying with any role, not clinging to anything, not following any particular thought. It is right here, where we sit. If we read everlasting as something like eternal, we are missing the mark. Because of the very reality of impermanence nothing can go for ever, and certainly not time. Everlasting might mean here, through changes and seasons, always available, always open for us. And practice- realization cannot be seen and compared to cherry blossoms in Spring, as you stop sitting, it carries on blossoming, as you sit,the whole,reality sits with you. Beyond the traditional idea of time, it is still sitting now. Flowers blooming Dogen uses a plural here because there is not a single you, we appear and disappear every signle moment, the person that sat in front of this screen and the person reading these lines are different. The feeling of continuity, a single self going through life, is a very nice illusion, we constantly disappear and reappear, and the speed of the process gives us a feeling of continuity. Constantly changing is our everlasting see how the first interpretation of his poem can be misleading, people reading this without the sitting experience would inevitably project a very dualistic and fake reading like: awakening is eternal and the trivial and dark reality of illusion cannot touch it. Countless springtimes will come and go, countless "you" will appear and die and yet, colors are always fresh, vibrant, vivid. Not because the flower lasts. Just the opposite.

All conditioned phenomena
Are like dreams, illusions, bubbles, or shadows;
Like drops of dew, or flashes of lightning;
Thusly should they be contemplated.

This verse of the Diamond sutra is generally understood as the sole description of how transitory and fast phenomena can is short.
Well, if I may, it describes exactly what Dogen points out, what is described here is not the duration of the phenomena but the speed of its transformation, before and after. As a young teenager, I remember reading an old copy of the diamond sutra in my bed at night time. i was mesmerized by this verse. But I could not undertand this, thinking my life as as fast as a flash of lightening. Now, countless flashes of lightening and endless flowers- lives.