In the first letter, dated 1 May 1857, Darwin commented that Wallace's letter of 10 October which he had recently received, as well as Wallace's paper "On the Law which has regulated the Introduction of New Species" of 1855, showed that they were both thinking alike and to some extent reaching similar conclusions, and said that he was preparing his own work for publication in about two years time.
Dalam surat pertamanya, tertanggal 1 Mei 1857, Darwin berkomentar bahwa surat Wallace tanggal 10 Oktober yang baru saja ia terima, serta makalah Wallace tahun 1855 yang berjudul "On the Law which has regulated the Introduction of New Species", memperlihatkan bahwa mereka berdua berpikiran sama dan sampai batas tertentu meraih kesimpulan yang sama; Darwin juga mengatakan bahwa ia sedang mempersiapkan karyanya sendiri untuk dipublikasikan dalam waktu kira-kira dua tahun lagi.