I have been accustomed to call this book (Psalms), I think not inappropriately, “An Anatomy of all the Parts of the Soul;” for there is not an emotion of which any one can be conscious that is not here represented as in a mirror. Or rather, the Holy Spirit has here drawn to the life all the griefs, sorrows, fears, doubts, hopes, cares, perplexities, in short, all the distracting emotions with which the minds of men are wont to be agitated. The other parts of Scripture contain the commandments which God enjoined his servants to announce to us. But here the prophets themselves, seeing they are exhibited to us as speaking to God, and laying open all their inmost thoughts and affections, call, or rather draw, each of us to the examination of himself in particular, in order that none of the many infirmities to which we abound, may remain concealed. It is certainly a rare and singular advantage, when all lurking places are discovered, and the heart is brought into the light, purged from that most baneful infection, hypocrisy. In short, as calling upon God is one of the principal means of securing our safety, and as a better and more unerring rule for guiding us in this exercise cannot be found elsewhere than in the Psalms, it follows, that in proportion to the proficiency which a man shall have attained in understanding them, will be his knowledge of the most important part of celestial doctrine. Genuine and earnest prayer proceeds first from a sense of need, and next, from faith in the promises of God. it is by perusing these inspired compositions, that men will be most effectually awakened to a sense of their maladies, and, at the same time, instructed in seeking remedies for their cure. In a word, whatever may serve to encourage us when we are about to pray to God, is taught us in this book. And not only are the promises of God presented to us in it, but oftentimes there is exhibited to us one standing, as it were, amidst the invitations of God on the one hand, and the impediments of the flesh on the other, girding and preparing himself for prayer: thus teaching us, if at any time we are agitated with a variety of doubts, to resist and fight against them, until the soul, freed and disentangled from all these impediments, rise up to God; and not only so, but even when in the midst of doubts, fears, and apprehensions, let us put forth our efforts in prayer, until we experience some consolation which may calm and bring contentment to our minds. Although distrust may shut the gate against our prayers, yet we must not allow ourselves to give way, whenever our hearts waver or are agitated with inquietude, but must persevere until faith finally come forth victorious from these conflicts. In many places we may perceive the exercise of the servants of God in prayer so fluctuating, that they are almost overwhelmed by the alternate hope of success and apprehension of failure, and gain the prize only by strenuous exertions. We see on the one hand, the flesh manifesting its infirmity; and on the other, faith putting forth its power; and if it is not so valiant and courageous as might be desired, it is at least prepared to fight until by degrees it acquire perfect strength. But as those things which serve to teach us the true method of praying aright will be found scattered through the whole of this Commentary, I will not now stop to treat of topics which it will be necessary afterwards to repeat, nor detain my readers from proceeding to the work itself. Only it appeared to me to be requisite to show in passing, that this book makes known to us this privilege, which is desirable above all others — that not only is there opened up to us familiar access to God, but also that we have permission and freedom granted us to lay open before him our infirmities which we would be ashamed to confess before men.
John Calvin (1509-64), The Author’s Preface, Joshua. Psalms 1-35, xxxvi-xxxvii