According to robert merton, what is the importance of using the conceptual scheme of
latent functions (unforeseen or unintended consequences) and manifest functions
(purposed consequences)?

Robert Merton (1910 – 2003) have made an extensive contribution to the theory of Structural functionalism. In particular, by sharpening the concepts of latent and manifest functions and applying them to sociology.

Merton was arguing that while studying a certain social phenomenon, it is important to identify both manifest and latent functions of this phenomenon.  

For example, looking at festivals, they appear to have manifest functions of cultural development and social bonding. Meanwhile, they also have latent function of excessive garbage production and traffic jams.  

in 342 bc j._c. egypt fell into the hands of the persians, under the reign of nectanebo ii

greek city-states unite in a revolt against the persian empire at the beginning of the fifth century bc. j.-c  

from the year 660 or 659 bc ad, cyrus preached the revolt against the medes to deliver the persians.