亘古通今

from ancient times up to now / throughout history

extending all the way across / running all the way through

throughout time / from ancient times (up to the present)

surname Gu

ancient / old / paleo-

to go through / to know well / (suffix) expert / to connect / to communicate / open / to clear / classifier for letters, telegrams, phone calls etc

classifier for an activity, taken in its entirety (tirade of abuse, stint of music playing, bout of drinking etc)

now / the present time / current / contemporary / this (day, year etc)