Learn English – the origin of the phrase “take it from the top?”

Warning: pure speculation.

It used to be that time spent connected to the network was very expensive. Back then, dealing with information to be processed offline was to use cheaper cycles to deal with that information. I most commonly hear this phrase in meetings, where a great deal of expensive engineer time is being wasted by details that only relate to 2 of the participants. Thus, taking the conversation offline is a metaphor for having the conversation on cheaper time.

The phrase is likely derived from the Latin cum grano salis, which in turn was used by Pliny the Elder in his work Naturalis historia:

After the defeat of that mighty monarch, Mithridates, Cneius Pompeius found in his private cabinet a recipe for an antidote in his own hand- writing ; it was to the following effect: Take two dried walnuts, two figs, and twenty leaves of rue ; pound them all together, with the addition of a grain of salt; if a person takes this mixture fasting, he will be proof against all poisons for that day.