These words describe the continual painstaking exertion of intense care and effort. Diligent suggests the accomplishment of work that is well done and that demands the worker’s alertness and dedication to the task: his diligent efforts to vindicate his father’s name. There is also an implication of wary watchfulness and the making of extremely fine distinctions: inspectors diligent enough to catch the slightest lowering of standards.

Sedulous is considerably more formal than diligent but also stresses attentiveness, with a special overtone of unwearying application to an exhausting task: a teacher who proceeded so rapidly that only the most sedulous student could follow him. Assiduous is only slightly less formal than sedulous ; it emphasizes the ability to do quantities of sheer hard work. There is less implication that the work is well done as in diligent or that it is extremely taxing as in sedulous . It does suggest dogged determination and an energetic approach: an assiduous struggle against the untamed land that every year brought forth more and more crops.

• A poorly edited book requires the reader’s sedulous attention to make up for the lack of diligent copy editing and assiduous proof-reading.

Persevering has an area of meaning that sets it more clearly apart from the foregoing words; it refers to an unremitting effort that is not weakened by momentary failures: to watch the persevering spider attempt to build her web time and time again. Persevering clearly indicates nothing about the quality or quantity of the work done, only about the unflagging nature of the effort: persevering in the typing assignment despite her exhaustion and her loss of accuracy and speed. Industrious also makes no comment upon the quality of the work accomplished but it does stress constancy or speed of execution. It also suggests a cheerful or good-humoured bustle: industrious clerks who turned out mountains of filing and paper work in just a few hours.