Now you understand why we had to first learn the yud, then the vav, and only then look at the alef. As we go through the alefbet, you'll see that not only the alef, but every letter, is a composite of the vav and different forms of the yud.
The alef, however, tells it all. Hey, look at this: Every letter of the alefbet has a numerical value. The alef--you guessed it--is 1. It also has another numerical value, because you can spell it out: Alef (1), Lamed (30), Feh (80) spells Alef in Hebrew letters. Add those up and you get 111. All three bases loaded with ones.
That's because the alef isn't just about oneness, it's about creating oneness. When there is nothing else but one that's not the real oneness. The real oneness is when there is more than one--there are at least two--and yet both find a common essence and come together as one. Which means the first step is that there is only one; the second step is that there are two; and the third step is that there are two that become one. One above, one below and one together makes three ones.
Practically speaking: I'm here on planet earth thinking there's nothing else but me. The Infinite Light (as we Kabbalists like to call Him) looks upon the whole scene and sees there is nothing else but Him. But then I realize, hey that's ridiculous, I didn't make this place, there must be someone way bigger than me behind all this. So I reach up to Him. Which was just what He was waiting for so that He could reach down to me. And so we are two that become one.
Now, you're asking, "How on earth does a meat and bones human being reach up to the Infinite Light?" The answer is that the Infinite Light set things up so that we have a whole repertoire of mitzvahs and beautiful deeds for connecting with. They look small and innocent enough, but in fact, they are all really trigger-points to elicit response from Above. He says, "Reach up to me by doing these things, and I will reach down to you in a similar way. Make light with a candle for Shabbat, and I will shine into your home. Give a coin to those in need, and I will give you life and the things you need. Put a mezuzah on your door, and I will protect you in all you do. Wrap these leather boxes with scrolls to connect your mind and heart, and I will focus my supernal mind and heart on you and your world. Turn to me in love, and I will mirror that love back to you--only that it will be in my infinitely unbounded terms."
That also explains Miri's puzzle: Why is it that the lower yud reaches high up, while the higher yud reaches way down? Well, it's because the higher I reach up to Him, the further down He reaches to me. To make the worlds of the angels one with the Infinite Light, you don't have to reach so high. But to take all the stuff of this everyday world of ours and make it one with Him, for that you have to reach very high indeed. Which is just what the ancient Book of Formation teaches: The lowest is connected to the highest and the highest is connected to the lowest.