Our "40 days" is a round number with symbolic meaning.  The Jews spend "40 Years" in the desert on their way to the Promised Land.  Jesus spent "40 days and 40 nights" fasting in the desert before beginning his ministry.   In the early centuries, the fasting days leading up to Easter varied - in some places two days, in others a week.   Gradually this grew longer and longer, and by the mid-fourth century, Lent began six weeks before Easter .However, fasting was always prohibited on Sunday, which meant that there were only 36 fasting days.  To resolve this, the Church added four days of fasting (Ash Wednesday and the Thursday, Friday, and Saturday after Ash Wednesday), thus giving us 40 days of fasting.   Lent itself ends on the evening of Holy Thursday.  We then begin the Triduum, the most sacred three days of the year, lasting through Easter Sunday evening.  


" The Little Black Book" 2005