You're most welcome, Flora, and I'm sorry to hear you weren't able to access two of the links. I happen to be in China (Daqing) at the moment, so, I understand about not being able to access certain sites. No matter, though. Here's what you requested. Please note, what follows is my interpretation. Hope it's close, and if not, at least serves to amuse.
Rabbi Ben Ezra doesn't view life as others do, as two opposing halves: Youth and Old Age. He explains this by drawing on direct opposites. (See below, the origin of the rose and the lily symbolism; Mars and Jove). His purpose in doing so it to show that Youth and Old Age are neither separate nor opposites but rather concentrically related, as is the inner blue flame within its outer, bright white flame, which he describes in the last line:
"Mine be some figured flame which blends, transcends them all!" Moving on to the symbolism. The rose and the lily (another term for the water lily or lotus) represent, in religious symbolism, spring, rebirth, fertility, and motherhood. The important point here is that the rose in the Western part of the world represents what the lily does in the Eastern part of the world. That symbolism is one and the same, but it originated from different parts of the world. They met a similar end, but did not share a similar beginning. Here we see two points joining as one. Rabbi Ben Ezra believes otherwise about how Youth and Old age are connected. Youth "sighed" amassing flowers,
"Which rose make ours, which lily leave and then as best recall?"In other words, Youth and Old Age aren't connected in that way and, moreover, shouldn't be viewed in that way. On the contrary, they are intertwined from the beginning. And they are not direct opposites either, like the "stars" Jove and Mars.
Jove and Mars are planets. Mars symbolizes the God of War, whereas Jove is better known as Jupiter, another name for the God of gods in Greek mythology, and Jehovah, in Semitic texts. Jove and Mars are direct opposites, antonyms, if you will: death, life; hate, love; black,white, the rashness of youth, the wisdom of old age. Youth and Old Age are not connected that way, tells Rabbi Ben Ezra, "It [Youth] yearned" admiring stars,
Nor Jove, nor Mars;All the best.
Mine be some figured flame which blends, transcends them all!"