The text presents a homiletic meditation on the characters of Martha and Mary as well as Comenius' seeking of the one thing necessary in his late writing Unum necessarium (1668). The one thing needful means above all to listen to one Lord and let oneself change by his Word.
The word is Jesus. A related thing is that one should pay attention mainly to the words, to the message, and thus also to the speaker.
Only then, it is advised, one should start various activities and make changes to the world. This cannot be done without a clear, yet free and conscious choice.
If that is made, a firm starting position for everything else is gained.