Eugene Nida has been a pioneer in the fields of Translation Theory and Linguistics.
His Ph.D. dissertation «A Synopsis of English Syntax» was the first full-scale analysis of a major language according to the «immediate «constituent» theory (Wikipedia)
His most notable contribution to Translation Theory is his work on Equivalence
Nida set out to rescue translation from the static and pointless literal vs. free translation debate using the science of language in translation. To accomplish that, he came out with the concept of ‘equivalence’. Although many doubt the usefulness of this concept, there is no doubt that ‘equivalence’ and ‘equivalent effect’ are key concepts in translation.
Formal and dynamic equivalence: Formal equivalence means “equivalence” in form. Because formal equivalence is centered on the form of the Source Text (ST), this type of equivalence is ST-oriented. According to Nida himself «..One is concerned that the message in the receptor language should match as closely as possible the different elements in the source language». On the other hand, Dynamic equivalence means “equivalence” free from the ST form (TT-oriented). It meets the linguistic and cultural needs of the receptor. Therefore, the translation is tailored to each particular addressee. Dynamic equivalence is based on what is called ‘equivalent effect’ which occurs when ‘the relationship between receptor and message is substantially the same as that which existed between the original receptors and the message’,(Nida) that is to say, the translator is encouraged to make changes in grammar, lexicon and cultural aspects so as to achieve a “natural” text for his receptor.