The Sojourn

This is a continuation from the Scholar achievement, which should leave you with 10 merits of life, so the next steps are very similar to gain another 10 so that you have 10 + 10 = 20 merits of life, which will pop this achievement as soon as you reach the platform that holds the twentieth merit of life. After going up a level from level 2 (which had 5 puzzles (only 4 of which had merits of life)), you will be brough to the third level, which contains 6 puzzles, each of which will provide another merit of life, so collect each merit of life on level 3 and you should have 16 merits of life by now. After gaining 16 merits of life and completing each puzzle on level three, you can escalate to the fourth level which contains two bonus puzzles, each of which gains you 1 merit of life (1 + 1 = 2), so you'll gain 2 there. Then there are two normal/game-critical levels of which the solution to both will gain you access to the next level up, but each also will provide another merit of life. So, with the two bonus level merits and these two, that brings you to 4 merits of life on this level, for a total of 16 + 4 = 20 merits of life. So after standing on the platform with your fourth merit of life, this achievement should pop.