Some aspects of human behavior haven’t changed through the centuries. St. Isaac the Syrian comments below on impetuousness of youth, something as observable today as it was 1400 years ago. Another phrase sometimes applied to such impetuosity comes from St. Paul – they have a zeal which is not enlightened (Romans 10:2).
St. Isaac is referring here to young monks who imagine themselves as being spiritual giants and geniuses whereas old monks with years of experience in the spiritual warfare would never make the claims of spiritual progress that the young inexperienced monks imagine for themselves. It often happens with people new in the faith as well. They read THE LADDER OF DIVINE ASCENT and though practicing the faith for only a few months rashly judge themselves already to have attained the top steps of the ladder and the heights of heaven. As St. Isaac says if they continue with their self-deception they will go insane – especially when they find themselves struggling with the most elementary aspects of virtue and purity.
“Even venerable elders, who from youth to old age have exhausted themselves with asceticism in the vineyard of the Son, practicing excellent disciplines, are scarcely accounted worthy of partially receiving one of the gifts of the land of peace. But youths, with the impetuosity of their nature and with disorderly fervor, audaciously rush upon the mysteries of the Fathers hidden in their books. Or else they receive by instruction and hearsay from others that which they ought not. Then grace cuffs them and educates them to delay and not to rush headlong upon lofty things, but, on the contrary, to labor quietly in the vineyard until such a time as they attain to true rest. If, however, they continue in their audacity, grace withdraws from them a little, and they are seized by ten thousand temptations. They are smitten by the passions of the body, the very same passions which they formerly held in contempt, and they are tormented by dark periods of soul and abused by the demons. Violent uprisings, as well as confusion and listlessness of mind, assail them. If they do not recollect themselves and put themselves in order, they will go insane. O how many afflictions, trials, snares, and stumbling blocks in this, our Lord’s, narrow way are arrayed against those who, with the impulses of nature, disorderly fervor, keen wits, and the accepting [or hearsay] from others, wish to enter the abode of life and partake of the honeycomb of the Spirit!” (The Ascetical Homilies of St. Isaac the Syrian, pg. 401)