At Newcastle there was a brief cessation from work, under the doctor's orders. But in the middle of 1828 Harriet began to write again for the _Repository_, in response to an appeal put forth by the editor for gratuitous literary aid. That editor was the well-known Unitarian preacher, William Johnston Fox, of South Place Chapel. Mr. Fox became Harriet Martineau's first literary friend. He had no money with which to reward her work for his magazine; but he paid her amply in a course of frank, full, and generous private criticism and encouragement. "His correspondence with me," she says, "was unquestionably the occasion, and, in great measure, the cause, of the greatest intellectual progress I ever made before the age of thirty." Mr. Fox was so acute a critic that he ere long predicted that "she would be one of the first authors of the age if she continued to write;" while, at the same time, he offered suggestions for improvement, and made corrections in her work upon occasion. Her advance in literary capacity was now very rapid. Her style went on improving, as it should do, till her latest years; but it now first became an _individual_ one, easy, flowing, forcible, and often most moving and eloquent. During the latter half of 1828 and the early part of the succeeding year, she contributed, more or less, to nearly every monthly number of the _Repository_, without receiving any payment. She wrote essays, poems, and so-called reviews, which last, however, were really thoughtful and original papers, suggested by the subject of a new book. Some of these contributions were signed "V"; but others, including all the reviews, were anonymous. Most of these articles are on philosophical subjects, and are written with the calmness of style suitable to logical and argumentative essays. In the _Repository_ for February, 1829, and the succeeding month, for instance, there appeared two papers, headed, "On the Agency of Feelings in the Formation of Habits," which are simply an accurate, clear, and forcibly-reasoned statement of the philosophical doctrine of Association, with which that of Necessity is inseparably connected. These were, it has been already observed, the theories by which she was learning both to guide her own action and to see that society is moulded, however unconsciously, as regards most of the individuals composing it. A clearer statement of the doctrines, or a more forcible indication of how they can be made to serve as a moral impulse, cannot be imagined. Here is very different work from _Devotional Exercises_, or _Principle and Practice_. But it brought its author neither fame nor money.