To be active and still at the same time is not a contradiction in terms. Just ask a percussionist in an orchestra. He might be called upon to play only a few times in a symphonic movement, while the rest of his sheet music indicates a necessary stillness. His stillness, however, is very active. He needs to remain fully engaged in the process of listening and watching for the appropriate time to strike the cymbals or play the timpani. His silence isn't a lack of participation; instead it's a vital contribution to the harmony of the music he plays. What a disruption to the progressive flow of the musical performance an unnecessary or mistimed cymbal crash would be!
As a musician's silence indicates more than just an absence of noise, so silent prayer is not merely a cessation of talking. Such prayer involves active knowing, active yearning, and an attitude of spiritual readiness that leaves one responsive to the divine influence.
"Prayer," the first chapter of Science and Health, brings out how important silence is at times. You find statements such as, "Thoughts unspoken are not unknown to the divine Mind" Science and Health, p. 1. and, "The unspoken desire does bring us nearer the source of all existence and blessedness." Ibid., p. 2. A particularly pointed statement is: "Audible prayer is impressive; it gives momentary solemnity and elevation to thought. But does it produce any lasting benefit?" Ibid., p. 7.