This is to acknowledge receipt of your letter with the enclosure, in which you write about your problem of acute anxiety, and ask my advice.
The best and most effective thing to do, in a situation such as yours, is to study thoroughly those sections and chapters in our sacred books where the matter of Divine Providence and Bitochon [trust] are discussed, such as Chovos Halvovos, Shaar Habitochon, and similar. It is well to keep in mind those chapters and verses in the Tehillim [Psalms] which speak of these subjects, as well as the Midrashim and interpretations of our Sages on them. These things should be studied with such depth that they should become a part of one's thinking. In this way there will be no room left for any kind of anxiety or worry, and as King David said in the Tehillim , "G-d is with me, I shall not fear. What can man do unto me!"
As you well know the matter of Hashgocho Protis [Divine Providence] is the basis of true monotheism, a concept which to us means not only that G-d is one, but also is the Master, continually supervising every detail of His handiwork. The corollary of this is that there cannot be a single point in the whole order of the world which is separated from the Supreme Being, or in any way not subject to His control. At the same time it is obvious that the Supreme Being is also the Essence of Perfection and Goodness. And although many things in the world seem imperfect, and require completion or perfection, there can be no doubt that there is a perfect order in the world, and even the lowest in the scale of Creation, namely the inanimate things, display wonderful perfection and symmetry, as can be seen from the atoms and molecules of inorganic matter. Hence, the conclusion must be that even those things which require completion, are also part of the perfect order, and necessary for the fulfillment of the good, as all this is explained at length in the teachings of Chassidus. It is explained there that in order for a man to attain perfection, it is necessary that he should also have the feeling that he is not only on the receiving end, but also a contributor, and according to the expression of our Sages of blessed memory, "A partner in the Creation." This is why many things have been left in the world for him to improve and perfect.