From the Supplement, compiled after Aquinas’s death from his Commentary on the Sentences and transcribed here from the 1917 to 1922 printings. About the Supplement.
Text: Summa Theologiae, Supplement to the Third Part (Supplementum Tertiae Partis), transcribed from Internet Archive scans, translated by the Fathers of the English Dominican Province. The Supplement, compiled after Aquinas’s death from his earlier Commentary on the Sentences, in the same English Dominican translation as the Gutenberg Parts. Transcribed by Bibliotheca Catholica from the OCR of four Internet Archive scans of the pre-1931 printings (Questions 1 to 33 from the 1917 Washbourne and Benziger volume, 34 to 68 from the 1922 volume, 69 to 86 from the 1921 volume, and 87 to 99 from the 1922 Benziger volume), with OCR errors corrected and doubtful passages marked, not rewritten. 99 questions and 446 articles. The two appendices printed after Question 99 are not included. Sources, SHA-256 of each OCR file, and the method are in the source record. Rights: Public domain (US)
The Supplement is not a Project Gutenberg text. It is Bibliotheca Catholica’s transcription of public-domain scans at the Internet Archive; obvious OCR errors were corrected, and passages marked “OCR uncertain” could not be confidently corrected, so check them against the linked scan page.
Objection 1: It seems that confession does not open Paradise. For different sacraments have different effects. But it is the effect of Baptism to open Paradise. Therefore it is not the effect of confession.
Obj. 2: Further, it is impossible to enter by a closed door before it be opened. But a dying man can enter heaven before making his confession. Therefore confession does not open Paradise.
On the contrary, Confession makes a man submit to the keys of the Church. But Paradise is opened by those keys. Therefore it is opened by confession.
I answer that, Guilt and the debt of punishment prevent a man from entering into Paradise: and since confession removes these obstacles, as shown above (AA. i, 2), it is said to open Paradise.
Reply Obj. 1: Although Baptism and Penance are different sacraments, they act in virtue of Christ's one Passion, whereby a way was opened unto Paradise.
Reply Obj. 2: If the dying man was in mortal sin Paradise was closed to him before he conceived the desire to confess his sin, although afterwards it was opened by contrition implying a desire for confession, even before he actually confessed. Nevertheless the obstacle of the debt of punishment was not entirely removed before confession and satisfaction.
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Also online, linked only: the same translation at New Advent and the Latin text at Corpus Thomisticum. Neither is copied here.