As for the quotation, it is taken from “My Life in Christ”, a book for which the cliche "a classic" doesn't come close to conveying its richness and spiritual depth.
Saint John of Kronstadt on Peace and Despair
July 2, 2009 by Andrew
St. John of Kronstadt
Sometimes in nature a warm, healthful wind blows, pleasantly and lightly, permeating and coming in contact with the body, and the sky is serene; whilst at other times a cold wind blows, one feels, somehow, distressed and feverish, the wind pierces to the very bones and affects the body unpleasantly, the earth and sky are darkened; or else sometimes the state of the atmosphere is warm and warmth-giving, and at other times cold, benumbing. It is likewise in the spiritual life: sometimes our soul is surrounded and penetrated by a light, pleasant, warmth-giving, vivifying breath, we feel ourselves happy and tranquil; whilst at others our heart is touched by a heavy, deathly breath, accompanied by complete spiritual darkness. The first state proceeds from the Spirit of God, the second from the Devil. It is necessary to accustom ourselves to everything: as in the first case, not to grow self-conceited, so in the last, not to fall into despondency, into despair, but to fervently have recourse to God.
* This excerpt was taken from the book “My Life in Christ” by St. John of Kronstadt
As is sometimes the case, this particular passage speaks closely to me in the present circumstances in which my life currently finds itself.