In the cosmology of Isaac Luria, the Ari, initially in the Creation there were vessels (kaylim) that were filled with light to a point where they could not contain this primordial light, and they burst. This process is called Shevirat haKaylim, the bursting of the vessels, which spread sparks of this infinite light across the universe.
In Luria's cosmology, the brilliant light that initially was uncontainable, ultimately became less concentrated and thus less forceful. In essence, the original became "sparks." These sparks are diminishments of the original light, and the whole purpose of creation in this cosmology is to raise these sparks up to the oneness of their original form. This is accomplished through good deeds, among other things.