It is a privilege to offer a work like this, for the first time, to Spanish-speaking readers. Thomas Goodwin (1600-1679), the great 17th-century English theologian, succeeded in dissecting with it the inner workings of something that every Christian should hold up as a model and example for life: the heart of Christ. It is no easy task, but Goodwin's ability to capture details and nuances provided by the Holy Scriptures, and his acute, yet natural, reasoning, result in a profound, rigorous work of great value for believers of any era and condition.