A successful lawyer and politician, he had a vision while being held hostage that called him out of that life into one of reformation, poverty, privation, and preaching. I am not sure how he got out of his marriage, perhaps his wife could just not put up with him anymore.
We all want to label our time as the worst, and look back or forward to other times and call them the best. As Jesus reminds us though, times just are what they are and now is the moment we live. By the time John came on the scene, 1/3 of the population in Europe including almost half of the clergy had been wiped out by the Bubonic Plague, confusion over spiritual power was rampant because there were several claimants to the papal throne, religious orders were fragmenting and in serious need of reform with much internal opposition to reform, and the whole continent was locked in a century long war, Italy was made up of divided, contentious, and warring city-states constantly vying for power; many people had lost their way and many other had even given up on God. The world that would influence Machiavelli was being born. Atheism and political and secular contention with the Church is nothing new.
Thinking about his life, what life do you think you would have been living at that time? What camp would you fall into when you looked at that world? I imagine that just like those times, people are the same now as they were then and the same thoughts and questions remain. They have the same doubts and fears, same hopes and dreams as we today. Would you still even believe in God?
John leapt into his world, so similar to our own with seemingly no place to turn for stability or comfort and with its lack of Faith and the seeking of solace in pleasure or descending into darkness and hopelessness.
Many were inspired by his preaching; they reformed their lives or turned toward Christ for the first time. While many flocked to his words, some may have been brought by forceful persuasion; hopefully the peace and mercy of Christ protected them and none were forced to convert and those that were fell back freely into following their own heart.
We do not fight a war of Faithlessness, nor a war of hopelessness and stumbling Faith; even when those of the clergy and religious life seem to lose their way, we do not chastise and condemn but call all to the Truth in Love, a cure for hopelessness and a reminder of the power and beauty of Faith. John did that then and reminds us to do it today.
And, technically, he has nothing to do with the swallows' migration path.
Those who are called to the table of the Lord must glow with the brightness that comes from the good example of a praiseworthy and blameless life. They must learn from the eminent teacher, Jesus Christ. . .“You are the light of the world” (Matthew 5:14). Now a light does not illumine itself, but instead it diffuses its rays and shines all around upon everything that comes into its view. So it must be with the glowing lives of upright and holy clerics. By the brightness of their holiness they must bring light and serenity to all who gaze upon them. They have been placed here to care for others. Their own lives should be an example to others, showing how they must live in the house of the Lord.
-- Exhortation to Priests