St. John Cassian: Nothing is to be preferred to love

 Just as nothing is to be preferred to love, then, so also, on the other hand, nothing is to be less esteemed than rage and wrath. For everything, however beneficial and necessary it may appear, should nonetheless be put aside in order to avoid the disturbance of anger, and everything that may seem inimical should be put up with and tolerated in order to maintain unharmed the tranquility of love and peace, for it must be believed that nothing is more destructive than anger and annoyance and nothing more beneficial than love.

+St. John Cassian, from The Conferences, Conference 16; On Friendship #7

St. John Cassian: On the Prayer "Thy will be done..."

 "Thy will be done on earth as it is in heaven." There cannot be a greater prayer than to desire that earthly things should deserve to equal heavenly ones. For what does it mean to say: "Thy will be done on earth as it is in heaven," if not that human beings should be like angels and that, just as God's will is fulfilled by them in heaven, so also all those who are on earth should do not their own but His will? No one will really be able to say this but him who believes that God regulates all things that are seen, whether fortunate or unfortunate, for the sake of our well-being, and that He is more provident and careful with regard to the salvation and interests of those who are His own than we are for ourselves.

+St. John Cassian, from The Conferences, conference 9 On Prayer XX.1

St. John Cassian: Struggle against the demon of anger

Our fourth struggle is against the demon of anger. We must, with God's help, eradicate his deadly poison from the depths of our souls. So long as he dwells in our hearts and blinds the eyes of the heart with his somber disorders, we can neither discriminate what is for our good, nor achieve spiritual knowledge, nor fulfill our good intentions, nor participate in true life; and our intellect will remain impervious to the contemplation of the true, divine light; for it is written, "For my eye is troubled because of anger" (Ps 6:7 LXX). Nor will we share in divine wisdom even though we are deemed wise by all men, for it is written: "Anger lodges in the bosom of fools" (Exxles 7:9). Nor can we discriminate in decisions affecting our salvation, even though  we are thought by our fellow men to have good sense, for it is written: "Anger destroys even men of good sense" (Prov 15:1 LXX). Nor will we be able to keep our lives in righteousness with a watchful heart, for it is written: "Man's anger does not bring about the righteousness of God" (James 1:20). Nor will we be able to acquire the decorum and dignity praised by all, for it is written: "An angry man is not dignified" (Prov 11:25 LXX).
If, therefore, you desire to attain perfection and rightly to pursue the spiritual way, you should make yourself a stranger to all sinful anger and wrath. Listen to what St. Paul enjoins: "Rid yourselves of all bitterness, wrath, anger, clamor, evil speaking and all malice" (Eph 4:31). In saying 'all' he leaves no excuse for regarding any anger as necessary or reasonable. If you want to correct your brother when he is doing wrong or to punish him, you must try to keep yourself calm; otherwise you yourself may catch the sickness you are seeking to cure and you may find that the words of the Gospel now apply to you: "Physician heal yourself" (Luke 4:23), or "Why do you look at the speck of dust in your brother's eye, and not notice the rafter in your own eye?"(Matt 7:3).
+St. John Cassian, from On the Eight Vices, #4 On Anger, in The Philokalia, V 1.

St. John Cassian: The contemplation of God

The contemplation of God is arrived at in numerous ways. For God is not known only through wondering at His incomprehensible substance, because that is still concealed in the hope of the promise, but He is also clearly perceived in the grandeur of the things that He has created, in reflecting upon His justice and in the assistance provided by His daily providence - namely, when we consider with most pure minds the things that He has accomplished with His holy ones over the course of generations; when with trembling heart we admire that power of His by which He governs, directs, and rules all things, as well as the vastness of His knowledge and the eye from which the secrets of hearts cannot be hidden; when we think that He knows the sands of the sea and that He has measured the number of the waves; when we contemplate with amazement the raindrops, the days and hours of the ages, how all things past and future are present to His knowledge; when we look with a kind of overwhelming wonder at His ineffable gentleness, by which He tolerates with unwearying patience the numberless crimes committed in His sight at each and every moment, and at the call through which He has received us, thanks to His mercy and not to our own already existing deserts, and finally at the many occasions of salvation that He has bestowed on those who are to be adopted - because He commanded that we should be born in such a way that grace and the knowledge of His law might be given us from our very cradles, and because He Himself, conquering the adversary in us, bestows on us eternal blessedness and everlasting rewards for the sole pleasure of His good will; and when, lastly, He accepted the dispensation of His incarnation for our salvation and extended the marvels of His mysteries to all peoples. There are also other innumerable things of this sort to contemplate, which come to our minds (where God is seen and grasped by a pure vision) in accordance with the character of our life and the purity of our heart. Certainly no one in whom there still dwells something of carnal desire will lay hold of these things eternally, because, as the Lord says: "You shall not be able to see my face, for no one shall see me and live" (Ex 33:20) - namely, to this world and to earthly desires.
+ St. John Cassian, from The Conferences, First Conference, XV.