The Guardian explains factors that necessitated his need for a temporary absence and what “sustained and comforted” him during that time period

To have been unable, owing to sad circumstances over which I have had no control, to keep in close and constant touch with you, the beloved children of 'Abdu'l-Bahá, since His passing from this world, is to me a cause of sad surprise and deep and bitter regret. To say that ever since the Dawn of a New Day has broken upon me I have in the least felt reluctant or disinclined to enter into relationship with every one of you, or felt indifferent to a Cause which is so close and dear to your hearts, would indeed betray every sentiment of love and fellowship which animates every one of us in our servitude to His Holy Threshold. It was rather my utter exhaustion, my profound feelings of sorrow, the overwhelming sense of my own position and responsibilities and the extreme pressure of work that have caused me to maintain such a long silence and seem forgetful of those brave and valiant lovers of the Master in that land.

Of the thoughts that sustained and comforted me during my hours of restful retirement was the realization, never dismissed from my mind, that in the German friends the Master will surely find loyal and grateful children who will repay the tender love and paternal care which He had for them with a devotion and service, so profound and lasting that will prove worthy of the many blessings that have been theirs in the past. (Shoghi Effendi, excerpt from a letter dated 17 December 1922 to the Baha’is of Germany; The Light of Divine Guidance v I, p. 7) (To see the entire letter please visist Messages to the Baha'i World)