to pay a visit to

to visit sb

(old) to go to the palace to see the emperor; (old) to go to the capital

deep and profound meaning

profoundly well-versed

to call (at sb's home) personally

level of mastery (of a skill or area of knowledge); (archaic) to pay a visit to sb

to make painstaking efforts (idiom); after much trouble; to work hard at sth