This paper is adopting a new approach to investigate the capabilities of pathological mirror elements in the ideal representation of active building-blocks and shows that the voltage mirror (VM) and current mirror (CM) are the basic pathological elements. The descriptions for the floating mirror elements in the nodal admittance matrix (NAM), using infinity-variables, are derived. The descriptions for nullator and norator using infinity-variables in the NAM are shown to represent special cases from the derived descriptions of the floating VM and the CM, respectively. Hence, new representations for the nullator and norator in terms of the floating VM and CM, respectively, are obtained. A systematic procedure for the derivation of pathological configurations to ideally represent various analog signal-processing properties featured by active building-blocks is presented. This systematic approach became plausible by virtue of the versatility offered by the NAM descriptions of floating mirror elements. Novel pathological configurations ideally describing most popular signal-processing properties that involve differential or multiple single-ended signals; like conversion between differential and single-ended voltages, differential voltage conveying, current differencing, differential current conveying, and inverting current replication; are derived systematically using this procedure. The resulting pathological configurations are shown to be constructed mainly using mirror elements and hence the capabilities of the mirrors as basic pathological elements are further demonstrated. Pathological representations for some active building-blocks, using the derived pathological sections, are presented as application examples. Copyright (C) 2008 John Wiley & Sons, Ltd.