Maharsha: Natural Prayer
The Maharsha (Kiddushin 29b) describes effective prayer as a natural part of creation. God instituted prayer, as part of His creation and therefore an answered prayer should not be understood as miraculous, but as a normal part of life.
His proof is that Abaye, the great Amora (Rabbi of the Talmud) allowed himself to send Rabbi Acha bar Yaakov on a dangerous mission. Abaye, explains the Maharsha, was convinced that his prayers for his student would be effective and therefore he was not relying on a miracle.
A further proof is that God ordered Moses to stop praying for admittance into the Land of Israel because one more prayer would have triggered the innate response to answer Moses’ prayer.