Harlequin

I think I have sussed it. For the longest time I thought it was the Harlequin as defined above, as that is the only definition I was aware of. I have discovered a rare related use of it as a transitive verb:

Verb. (transitive) To remove or conjure away, as if by a harlequin's trick.

The song could be about Summer turning into Winter. The picture in the album is a painting of a woman, who is looking at tiny dancing figures. These could be the pale cold figures who spin a grey web - from the Fire of Summer to the Cold Grey of Winter? - who could also be the three children. She could be Mother Nature, governing the seasons, and overlooking her children (Humanity) as they dance in celebration of the seasons. Having once reaped a Harvest, it would seem that Harvest Season is over, even though Summer sticks around in the fires made to keep the cold of Winter at bay.

The term Harlequin could refer to conjuring away one season into another. That the reaping also refers to living and dancing during the day in the light, which is conjured away with the night. Perhaps the Children are there during the day, and the Cold figures are like faery-folk that come to dance at night, like Winter's helpers. The dancing still could seem to relate to the Harlequin character, who was supposed to be quite physical in the commedia dell'arte. Also, the shattered picture and pieces of the sky meant to be "put back" into place could refer to the multitude of triangles on one of the traditional costumes of the Harlequin character.

In the end, it seems to point to the idea that dawn will come again, and thus day. And thus viewed as a larger cycle, the Seasons will come around again to Spring and the warmth of another Summer.