Akhil becomes surety to Chandan for Bhushan's conduct as a manager of Chandan's bank. Afterwards,…

Akhil is not liable for the loss arising after the unauthorized variation of the manager's contractual obligations. Section 133 discharges a surety concerning transactions subsequent to a variance made without the surety's consent in the contract between the principal debtor and creditor.

Why not "wholly liable."? A surety's ordinary liability can be coextensive with that of the principal debtor, but it remains subject to the statutory rules of discharge. Here the creditor and manager changed their contractual arrangement without Akhil's consent, so the later overdraft loss cannot be imposed wholly on him.

Why not "liable to the extent of one-fourth of the loss."? The agreement making the manager responsible for a quarter of overdraft losses was made between Bhushan and Chandan alone. It does not create a corresponding quarter share of liability for Akhil, whose consent was absent and whose guarantee is discharged for transactions after the contractual variance.

Why not "liable to the extent of three-fourths of the loss."? There is no rule allocating the remaining three quarters of this loss to the original surety after the manager accepts a quarter share. The relevant consequence is discharge for subsequent transactions because the guaranteed contractual relationship was varied without the surety's consent, rather than an arithmetic division of liability.