Enquiry on Rectifier Circuit Using Op Amp

can anyone explain to me pls. i dont understand this line on page 3. "shown in Figure 5 becomes negative, the diode is forward biased holding the non-inverting input of A2 at virtual ground. A2, R1 and R2 form a simple unity-gain inverting
amplifier as before."

When the input to inverting amplifier A1 (Vin) goes negative the output of inverting amplifier A1 will go positive until diode D1 is forward balanced and that positive signal's current reaches A1's inverting input and restores balance to A1's inputs. In this state of balance A1's non-inverting input is tied to ground and A1's inverting input is held at a virtual ground.

thx for your reply. so can i say that when -5V enters input inverting of the A1, the output will be +5(inverted signal). Then it output of the diode (+5V) cancel of the -5V input voltage, which make the non-inverting input of A2 to become virtual ground 0V. can i say it this way?

i have simulated the circuit for figure 5 i found out that, the capacitor is to reduce the negative offset but i cant figure out how the capacitor really works in the circuit for Figure? Can anyone explain? thx...