Swami Brahmavid: What Swami Vivekananda is talking about is largely the power of samadhi, the capacity of the mind to respond and to and open to external influences, as well as the capacity to respond to and open to the Divine source within. It's the combination of the internal Divine stimulus and the external Secular stimulus which gives rise to the growth in consciousness, the ultimate direction being a realization of the Divine, residing within and behind everything.
The exhaltation we experience when we grow personally isn't because of the power of external situations. It only seems this way. Our exhaltation rises out of touching and momentarily expanding from within. We're touching Source whenever we learn something new, grapple with a problem and surmount it, etc. It's all really inward. Check it out for yourself. In fact, how could it be otherwise?
Swami Brahmavidyananda