Sutra:
126. ippOthu ivaLais sollugiRathu purushakAramAga.

Meaning:
Mahalakshmi is taken up in the first part of Dvaya because of Her nature of mediating (purushakAram).

Sri PBA Swami's Sarartha Deepikai:
Just as He has the two qualities of means (upAyatvam) and the end (upEyatvam), so too She has the two qualities of mediation (purushakAratvam) and the end (upEyatvam). Here, in the first part of Dvaya mantra, She is mentioned because of the quality of purushakAratvam.