You can feel it's presence but you cannot physically see it. You might see it's effect; but, when it's gone you can't see where it went nor can you see where it's been. You can only witness it's presence and appreciate it's effect (or loath it as the case may be). It's stronger than all of us and has no physical form. Wind builds pressure in the ears but the spirit builds pressure within the heart. The spirit isn't heard speaking to the man; but if the spirit effects the man, then the effect of it will be seen in the fruit produced by the ministry. The spirit is unseen but the effect of the coming and going is unmistakeable.
Yeah, that was about what I was thinking and I agree up to a point. That point being the latter part of that verse. Here's the verse again ...
The wind blows where it wills, and you hear the sound of it, but you do not know whence it comes or whither it goes;
Up to there, our assessment makes sense. But what of the following ... ?
so it is with every one who is born of the Spirit.
Now, are we (as those born of the Spirit) like the wind? Does no one know from where we come or where we go? Is this relating to Jesus telling the disciples "Where I am going, you cannot follow."