You aim at a devout life, dear child, because as a Christian you know that such devotion is most acceptable to God’s Divine Majesty. But seeing that the small errors people are wont to commit in the beginning of any under taking are apt to wax greater as they advance, and to become irreparable at last, it is most important that you should thoroughly understand wherein lies the grace of true devotion;—and that because while there undoubtedly is such a true devotion, there are also many spurious and idle semblances thereof; and unless you know which is real, you may mistake, and waste your energy in pursuing an empty, profitless shadow. Arelius was wont to paint all his pictures with the features and expression of the women he loved, and even so we all colour devotion according to our own likings and dispositions. One man sets great value on fasting, and believes himself to be leading a very devout life, so long as he fasts rigorously, although the while his heart is full of bitterness;—and while he will not moisten his lips with wine, perhaps not even with water, in his great abstinence, he does not scruple to steep them in his neighbour’s blood, through slander and detraction. Another man reckons himself as devout because he repeats many prayers daily, although at the same time he does not refrain from all manner of angry, irritating, conceited or insulting speeches among his family and neighbours. This man freely opens his purse in almsgiving, but closes his heart to all gentle and forgiving feelings towards those who are opposed to him; while that one is ready enough to forgive his enemies, but will never pay his rightful debts save under pressure. Meanwhile all these people are conventionally called religious, but nevertheless they are in no true sense really devout.
That one point, "we all color devotion according to our own likings and dispositions", is one of the most important things to grasp when dealing with religious devotion at all. As St. Francis goes on to note, devotion cannot be determined from any particular practice, which is often just a matter of taste; one only has devotion when one has a genuine love of God acting "carefully, diligently, and promptly".