John Calvin Commentary Luke 2:19

"But Mary kept all these sayings, pondering them in her heart." — Luke 2:19 (ASV)

Now Mary kept: Mary’s diligence in contemplating the works of God is set before us for two reasons: first, to inform us that this treasure was stored in her heart, to be shared with others at the appropriate time; and, secondly, to offer all the godly an example to follow.

For, if we are wise, it will be the primary task, and the main goal of our lives, to consider with attention those works of God that build up our faith.

Mary kept all these things. This relates to her memory. Συμβάλλειν means to throw together—to collect the various events that confirmed the glory of Christ, so that they might form a unified whole.

For Mary could not wisely assess the collective significance of all those events, except by comparing them with each other.