Oratory as form of vocation discussed by Crassus, in Cicero’s On Oratory and Orators, is defined as a calling – a profession an individual embodies. καλέω or kaleo is roughly translated to English as “to call” or “a calling.”  The path in which these two vastly different words are linked appears disconnected, through multiple languages and roots, they meet up. Vocation, from Latin vocatio means "a calling," from "vocatus” – with a base of “vocare”, meaning "to call." The original Proto-Indo-European root, wekw, turns up in Latin vox, meaning "voice.” In Greek, this root was reshaped into the word “epos”, which is broken down into “epic” and “ops”, meaning voice. The root ops can be found in "calliope" from the Greek word kalliope, meaning "beautiful voiced" and combines kalos "beautiful" and ops "voice." Kalo or καλῶ is derived from kaleo. 
A more modern definition for vocation is “an occupation to which a person is specially drawn or for which they are suited, trained or qualified.” This modern definition is a far cry for the original meaning in which individuals were summoned to an arguably honorable and influential career choice or lifestyle. Today's word simply conjures up thoughts of an alternative to a traditional four-year college. This shift in definition stemmed from the increase in vocational colleges over the past century across the states. From 1917 to 1998 thousands of Vocational-Technical Schools have been established in communities throughout the United States through three phases through the Smith-
Hughes Act, School-to-Work Opportunities Act, and the Carl D. Perkins Vocational and Technical Act  The U.S. Department of Education reports: “Virtually every high school student takes at least one vocational education course, and one in four students take three or more courses in a single program area. One-third of college students are involved in vocational programs, and as many as 40 million adults engage in short-term post-secondary occupational training.”  But this isn’t just an American concept. Currently, in Greece, I.E.K.’s – or Ινστιτούτο Επαγγελματικής Κατάρτισης – consist of public ad private vocational training in 14 different sectors, including telecommunications, tourism-transport, food and drink industry, clothing-footwear, applied arts, etc.
In On Oratory and Orators, Crassus accuses Antonius of “making our orator a mere mechanic,” by simplifying the process. After comparing orators, clergy and soldiers to mechanics and others we would lump into the modern definition of vocation, it is clear the term has been watered down significantly to apply to almost all careers, not just those that really define the individual through their responsibility to society.