Prayer is the buttress of faith, our armor and weaponry against the enemy that watches us from every side. So never let us set out unarmed— let us remember the station by day and the vigil by night. Let us guard the standard of our emperor armed with prayer, awaiting the trumpet of the angel while we pray. Indeed, every angel prays, every creature. The herds and the wild beasts pray and bend their knees, coming forth from byres and dens looking to heaven, giving movement to the spirit after their fashion with animated mouths. And even now the birds arise, lifting themselves to heaven, spreading out their wings like a cross whilst utter- ing what appears to be a prayer. What more might be said on the duty of prayer? Even the Lord himself prayed, and to him be honor and might for ever and ever.
Oratio murus est fidei, arma et tela nostra aduersus hostem qui nos undique obseruat. Itaque nunquam inermes incedamus. Die stationis, nocte uigiliae meminerimus. Sub armis orationis signum nostri imperatoris custodiamus, tubam angeli exspectemus orantes. Orant etiam angeli omnes, orat omnis creatura, orant pecudes et ferae et genua declinant et egredientes de stabulis ac speluncis, ad caelum non otiosi ore suspiciunt uibrantes spiritum suo mouere. Sed et aues nunc exsurgentes eriguntur ad caelum et alarum crucem pro manibus expandunt et dicunt aliquid quod oratio uideatur. Quid ergo amplius de officio orationis? Etiam ipse Dominus orauit, cui sit honor et uirtus in saecula saeculorum. (Tertullianus, De Oratione, XXIX; trans.)