R. Soloveitchik in Halakhic Man (pp. 108-109):

If a man wishes to attain the rank of holiness, he must become a creator of worlds. If a man never creates, never brings into being anything new, anything original, then he cannot be holy unto his God. That passive type who is derelict in fulfilling his task of creation cannot become holy. Creation is the lowering of transcendence into the midst of our turbid, coarse, material world; and this lowering can take place only through the implementation of the ideal Halakhah in the core of reality (the realization of Halakhah=contraction=holiness=creation).