Source: John Collier
The University of Cambridge has recently published all of Charles Darwin's personal correspondence, including 400 letters that either surfaced or are newly "reinterpreted." This searchable collection covers over 15,000 letters between 1822 and 1882, so you can read everything from his time aboard the HMS Beagle to On the Origin of Species and end-of-life reflections.
And this archive could be the only way to get a fuller picture of the evolutionary scientist's life. The university noted the final print edition, due in early 2023, doesn't include letters that arrived too late to reach physical copies.