"Sommerfrische" is difficult to translate. It means much more than "summer retreat" or "summer holiday". It is strongly connected to vacation spent in a fresh climate (like the North or Baltic Sea), not in the tropics or subtropics. It evokes images like turn-of-the-century-women dressed in white clothes with big sunhats and children in blue and white striped sailor suits.
It means idleness, "to be at leisure", to think about one's life, to let your thoughts sail with the summer clouds.